I bought a second hand dji phantom 3 pro and when i turn the rc on it glows with red light. When i try to link the rc to the drone my phone says "remote controller signal weak" but i can put the rc into link mode. However my p3p just blinks 2 green and does nothing when i press the button on the downward visioning system (the led next to the button does not glow red or green, it doesnt even light up). What should i do?

Our apologies for the inconvenience. Can you provide a sample video of the issue so that we can check the exact status of the drone and remote controller? You can upload it by using google-drive or Dropbox and provide the link here. Thank you for your support.

in the meantime i tried a firmware update like 4 times (all 4 times failed) before i had enough and checked the log file wich said the gimbal devices detected but the others not (like battery, escs etc.). i flew with it the other week and now half of my copter is broke. is there a big chance that only the cable is faulty?
here is the video you asked for but it wont be of much help after you see the content of the log file.
video
here is the log file (i just copied the last 9 update):



[00555898]Version checking[2]...
[00556009][03 06][05] v2.4.20.50 -> v2.4.20.50
[00556141][03 05][00] v34.2.0.9 -> v34.2.0.9
[00556223][04 00][00] v1.48.0.0 -> v1.48.0.0
[00556386][11 00][00] v1.8.0.0 -> v1.8.0.0
[00556560][11 01][00] v1.8.0.0 -> v2.0.0.33, firmware v1.8.0.0 not support.
[00556739][11 01][00] v1.8.0.0 -> v2.0.0.33
[00556862][12 00][00] v1.12.0.0 -> v1.12.0.0
[00556994][12 01][00] v1.12.0.0 -> v1.12.0.0
[00557115][12 02][00] v1.12.0.0 -> v1.12.0.0
[00557229][12 03][00] v1.12.0.0 -> v1.12.0.0
[00557389][15 00][00] v1.1.2.0 -> v1.1.2.0
[00557549][17 00][00] v1.1.1.7 -> v1.1.1.7
[00557704][17 01][00] v1.0.2.7 -> v1.0.2.7
[00557795][19 00][00] v1.0.8.96 -> v1.0.8.96
[00557866][01 00][00] v1.32.5432 -> v1.32.5432
[00558082][01 01][00] v1.32.5432 -> v1.32.5432
[00558170][08 00][00] v0.13.0.7 -> v0.13.0.7
[00558275][09 00][05] v4.1.0.0 -> v4.1.0.0
[00558350]Packet upgrade finish successfully.



[00014534]========== 2017.09.26 18:23:33. boot(15) ============
[00014604]Packet [C:\P3X_FW_V01.11.0020.bin] detected, card sn [0x00001602].
[00014682]Packet upgrade start...

[00014755]Packet checking...
[00014823]Packet vlink 01.11.0020 <-> 01.11.0020.
[00014893]Record vlink 01.11.0020 <-> 01.11.0020 (flow = 0).
[00014963]Done.

[00015035]Version checking[1]...
[00015144][03 06][00] v2.4.20.50 -> v2.4.20.50
[00015248][03 05][00] v34.2.0.9 -> v34.2.0.9
[00015324][04 00][00] v1.48.0.0 -> v1.48.0.0
[00015464][11 00][00] v1.8.0.0 -> v1.8.0.0
[00015604][11 01][00] v1.8.0.0 -> v2.0.0.33, firmware v1.8.0.0 not support.
[00015676][11 01][00] v1.8.0.0 -> v2.0.0.33
[00015794][12 00][00] v1.12.0.0 -> v1.12.0.0
[00015926][12 01][00] v1.12.0.0 -> v1.12.0.0
[00016032][12 02][00] v1.12.0.0 -> v1.12.0.0
[00016133][12 03][00] v1.12.0.0 -> v1.12.0.0
[00016297][15 00][00] v1.1.2.0 -> v1.1.2.0
[00016407][17 00][00] v1.1.1.7 -> v1.1.1.7
[00016572][17 01][00] v1.0.2.7 -> v1.0.2.7
[00016673][19 00][00] v1.0.8.96 -> v1.0.8.96
[00016748][01 00][00] v1.32.5432 -> v1.32.5432
[00016816][01 01][00] v1.32.5432 -> v1.32.5432
[00016908][08 00][00] v0.13.0.7 -> v0.13.0.7
[00016994][09 00][00] v4.1.0.0 -> v4.1.0.0
[00017067]Packet upgrade cancelled at version checking.



[00014020]========== 2017.09.27 16:15:28. boot(15) ============
[00014210]Packet [C:\P3X_FW_V01.11.0020.bin] detected, card sn [0x00001602].
[00014282]Packet upgrade start...

[00014353]Packet checking...
[00014428]Packet vlink 01.11.0020 <-> 01.11.0020.
[00014500]Record vlink 01.11.0020 <-> 01.11.0020 (flow = 0).
[00014566]Done.

[00014645]Version checking[1]...
[00014758][03 06][00] v2.4.20.50 -> v2.4.20.50
[00014877][03 05][00] v34.2.0.9 -> v34.2.0.9
[00014950][04 00][00] v1.48.0.0 -> v1.48.0.0
[00015096][11 00][00] v1.8.0.0 -> v1.8.0.0
[00015260][11 01][00] v1.8.0.0 -> v2.0.0.33, firmware v1.8.0.0 not support.
[00015331][11 01][00] v1.8.0.0 -> v2.0.0.33
[00015446][12 00][00] v1.12.0.0 -> v1.12.0.0
[00015584][12 01][00] v1.12.0.0 -> v1.12.0.0
[00015710][12 02][00] v1.12.0.0 -> v1.12.0.0
[00015836][12 03][00] v1.12.0.0 -> v1.12.0.0
[00016001][15 00][00] v1.1.2.0 -> v1.1.2.0
[00016122][17 00][00] v1.1.1.7 -> v1.1.1.7
[00016279][17 01][00] v1.0.2.7 -> v1.0.2.7
[00016373][19 00][00] v1.0.8.96 -> v1.0.8.96
[00016445][01 00][00] v1.32.5432 -> v1.32.5432
[00016517][01 01][00] v1.32.5432 -> v1.32.5432
[00016609][08 00][00] v0.13.0.7 -> v0.13.0.7
[00016711][09 00][00] v4.1.0.0 -> v4.1.0.0
[00016778]Packet upgrade cancelled at version checking.



[00014257]========== 2017.09.27 16:17:42. boot(15) ============
[00014326]Packet [C:\P3X_FW_V01.11.0020.bin] detected, card sn [0x00001602].
[00014397]Packet upgrade start...

[00014473]Packet checking...
[00014545]Packet vlink 01.11.0020 <-> 01.11.0020.
[00014612]Record vlink 01.11.0020 <-> 01.11.0020 (flow = 0).
[00014690]Done.

[00014762]Version checking[1]...
[00014879][03 06][00] v2.4.20.50 -> v2.4.20.50
[00014979][03 05][00] v34.2.0.9 -> v34.2.0.9
[00015074][04 00][00] v1.48.0.0 -> v1.48.0.0
[00015220][11 00][00] v1.8.0.0 -> v1.8.0.0
[00015399][11 01][00] v1.8.0.0 -> v2.0.0.33, firmware v1.8.0.0 not support.
[00015477][11 01][00] v1.8.0.0 -> v2.0.0.33
[00015607][12 00][00] v1.12.0.0 -> v1.12.0.0
[00015744][12 01][00] v1.12.0.0 -> v1.12.0.0
[00015955][12 02][00] v1.12.0.0 -> v1.12.0.0
[00016062][12 03][00] v1.12.0.0 -> v1.12.0.0
[00016257][15 00][00] v1.1.2.0 -> v1.1.2.0
[00016382][17 00][00] v1.1.1.7 -> v1.1.1.7
[00016548][17 01][00] v1.0.2.7 -> v1.0.2.7
[00016638][19 00][00] v1.0.8.96 -> v1.0.8.96
[00016714][01 00][00] v1.32.5432 -> v1.32.5432
[00016783][01 01][00] v1.32.5432 -> v1.32.5432
[00016876][08 00][00] v0.13.0.7 -> v0.13.0.7
[00016958][09 00][00] v4.1.0.0 -> v4.1.0.0
[00017028]Packet upgrade cancelled at version checking.



[00012618]========== remo-con disconnect. boot(15) ============
[00012684]Packet [C:\P3X_FW_V01.11.0020.bin] detected, card sn [0x70a15d71].
[00012752]Packet upgrade start...

[00012821]Packet checking...
[00012886]Packet vlink 01.11.0020 <-> 01.11.0020.
[00012953]Record vlink 01.11.0020 <-> 01.11.0020 (flow = 0).
[00013019]Done.

[00013086]Version checking[1]...
[00025654][03 06][00] device not detected.
[00038219][03 05][00] device not detected.
[00038321][04 00][00] v1.48.0.0 -> v1.48.0.0
[00050888][11 00][00] device not detected.
[00063453][11 01][00] device not detected.
[00076017][12 00][00] device not detected.
[00088582][12 01][00] device not detected.
[00101147][12 02][00] device not detected.
[00113712][12 03][00] device not detected.
[00116797][15 00][00] device not detected.
[00129364][17 00][00] device not detected.
[00141934][17 01][00] device not detected.
[00154499][19 00][00] device not detected.
[00154564][01 00][00] v1.32.5432 -> v1.32.5432
[00154632][01 01][00] v1.32.5432 -> v1.32.5432
[00157215][08 00][00] v0.13.0.7 -> v0.13.0.7
[00169782][09 00][00] device not detected.
[00169847]Packet upgrade failed at version checking.



[00012627]========== remo-con disconnect. boot(15) ============
[00012692]Packet [C:\P3X_FW_V01.11.0020.bin] detected, card sn [0x70a15d71].
[00012758]Packet upgrade start...

[00012828]Packet checking...
[00012893]Packet vlink 01.11.0020 <-> 01.11.0020.
[00012959]Record vlink 01.11.0020 <-> 01.11.0020 (flow = 0).
[00013127]Done.

[00013193]Version checking[1]...
[00025762][03 06][00] device not detected.
[00038328][03 05][00] device not detected.
[00038405][04 00][00] v1.48.0.0 -> v1.48.0.0
[00050973][11 00][00] device not detected.
[00063539][11 01][00] device not detected.
[00076104][12 00][00] device not detected.
[00088668][12 01][00] device not detected.
[00101233][12 02][00] device not detected.
[00113798][12 03][00] device not detected.
[00116805][15 00][00] device not detected.
[00129372][17 00][00] device not detected.
[00141938][17 01][00] device not detected.
[00154503][19 00][00] device not detected.
[00154569][01 00][00] v1.32.5432 -> v1.32.5432
[00154637][01 01][00] v1.32.5432 -> v1.32.5432
[00154713][08 00][00] v0.13.0.7 -> v0.13.0.7
[00167280][09 00][00] device not detected.
[00167346]Packet upgrade failed at version checking.



[00012628]========== remo-con disconnect. boot(15) ============
[00012694]Packet [C:\P3X_FW_V01.01.0008.bin] detected, card sn [0x70a15d71].
[00012760]Packet upgrade start...

[00012831]Packet checking...
[00012896]Packet upgrade failed at packet checking.



[00012632]========== remo-con disconnect. boot(15) ============
[00012698]Packet [C:\P3X_FW_V01.11.0020.bin] detected, card sn [0x70a15d71].
[00012765]Packet upgrade start...

[00012835]Packet checking...
[00012901]Packet vlink 01.11.0020 <-> 01.11.0020.
[00012967]Record vlink 01.11.0020 <-> 01.11.0020 (flow = 0).
[00013034]Done.

[00013101]Version checking[1]...
[00025666][03 06][00] device not detected.
[00038231][03 05][00] device not detected.
[00038307][04 00][00] v1.48.0.0 -> v1.48.0.0
[00050873][11 00][00] device not detected.
[00063439][11 01][00] device not detected.
[00076004][12 00][00] device not detected.
[00088570][12 01][00] device not detected.
[00101136][12 02][00] device not detected.
[00113700][12 03][00] device not detected.
[00116802][15 00][00] device not detected.
[00129439][17 00][00] device not detected.
[00142005][17 01][00] device not detected.
[00154571][19 00][00] device not detected.
[00154637][01 00][00] v1.32.5432 -> v1.32.5432
[00154707][01 01][00] v1.32.5432 -> v1.32.5432
[00157283][08 00][00] v0.13.0.7 -> v0.13.0.7
[00169850][09 00][00] device not detected.
[00169915]Packet upgrade failed at version checking.



[00012629]========== remo-con disconnect. boot(15) ============
[00012695]Packet [C:\P3X_FW_V01.11.0020.bin] detected, card sn [0x70a15d71].
[00012761]Packet upgrade start...

[00012832]Packet checking...
[00012897]Packet vlink 01.11.0020 <-> 01.11.0020.
[00012963]Record vlink 01.11.0020 <-> 01.11.0020 (flow = 0).
[00013030]Done.

[00013096]Version checking[1]...
[00025662][03 06][00] device not detected.
[00038226][03 05][00] device not detected.
[00038302][04 00][00] v1.48.0.0 -> v1.48.0.0
[00050868][11 00][00] device not detected.
[00063433][11 01][00] device not detected.
[00075998][12 00][00] device not detected.
[00088564][12 01][00] device not detected.
[00101131][12 02][00] device not detected.
[00113696][12 03][00] device not detected.
[00116659][15 00][00] device not detected.
[00129223][17 00][00] device not detected.
[00141788][17 01][00] device not detected.
[00154353][19 00][00] device not detected.
[00154419][01 00][00] v1.32.5432 -> v1.32.5432
[00154486][01 01][00] v1.32.5432 -> v1.32.5432
[00154565][08 00][00] v0.13.0.7 -> v0.13.0.7
[00167133][09 00][00] device not detected.
[00167197]Packet upgrade failed at version checking.



[00012649]========== remo-con disconnect. boot(15) ============
[00012714]Packet [C:\P3X_FW_V01.11.0020.bin] detected, card sn [0x70a15d71].
[00012781]Packet upgrade start...

[00012851]Packet checking...
[00012915]Packet vlink 01.11.0020 <-> 01.11.0020.
[00012982]Record vlink 01.11.0020 <-> 01.11.0020 (flow = 0).
[00013050]Done.

[00013116]Version checking[1]...
[00025684][03 06][00] device not detected.
[00038351][03 05][00] device not detected.
[00038428][04 00][00] v1.48.0.0 -> v1.48.0.0
[00050995][11 00][00] device not detected.
[00063562][11 01][00] device not detected.
[00076127][12 00][00] device not detected.
[00088692][12 01][00] device not detected.
[00101256][12 02][00] device not detected.
[00113820][12 03][00] device not detected.
[00116994][15 00][00] device not detected.
[00129561][17 00][00] device not detected.
[00142126][17 01][00] device not detected.
[00154692][19 00][00] device not detected.
[00154757][01 00][00] v1.32.5432 -> v1.32.5432
[00154824][01 01][00] v1.32.5432 -> v1.32.5432
[00154909][08 00][00] v0.13.0.7 -> v0.13.0.7
[00167475][09 00][00] device not detected.
[00167541]Packet upgrade failed at version checking.