Hello
i have bought a mavic air from ebay with water damage.
Opened the drone, cleaned both the mail board and the ESC board in ultasonic clener. everything looks good.
Checked the boards for any short circuits, reasmbled everything for the final test.
The drone powered up but only one motor did the beep sound and the drone can up with the back light red.
I have connected to the drone and everything seems to work except the main thing...the motors.
I get ESC error on all 4 motors: 1No.ESC Error , 2No.ESC Error, 3No.ESC Error, 4No.ESC Error
i checked every motor with and other ESC, an RC ca esc i had on hand, and all motors seem to work
Now the big Question...IF i change the ESC Power board...will this solve my problem? or the problem may be also the Main Board? i am not shure if the Main Board is to blame, hence all other functions work(camersa sensors, gimbal, live video, GPS, WIFI)
Any help would be appreciated.

P.S. i am a tech guy, i own a laptop service and big fan of RC cars, experience in electronics, but not in these drones!

The damage could be at miniature wiring harness quick disconnects burning traces bridged by seasalt. You need schematic to understand logicboard command onto dc controllerboard that gates loads energy prescribed.  The power distribution must have dedicated route for propulsion since large and preventing logic load perturb by reactive current

1st of all water damage depends on the water it was exposed to..

salt water is more or less not even worth it.. as someone who has worked on both vehicals and electronics that been exposed to saltwater flooding, cut your losses....salt water is so destructive, even if its powered off..   i seen wiring that was perfectly fine on each end but rotting out in the middle under rubber coating..wouldn't have seen it  it also works its way under componets and may eat away balls under any BGA packaging maybe out of sight..  

fresh water, if the device was exposed to fresh water flooding, recovery is possible. assuming whoever crashed it into fresh water didn't leave it powered on too long.. i recovered many devices and even partially restored vehicals been flooded by fresh water..

pool water (chlorine) is surprisingly very corrosive as well..about as bad as partially salty water...so if its exposed tot hat and pulled quickly, powered off and left to dry out, it can survive, but if it was left there for a period of time or not given enough time to dry out it can destroy parts..

finally...  ESC board isn't tied to specific serial number, however you will need to refresh your firmware a few times with new board and when you go to solder in the motors power leads, use plenty of flux so easier to form nearly perfect spheres of solder attaching them, no sharp points or angles as that can cause EMI to other systems..

thanks for you answers, but what I was looking for was for someone that may had the same errors and how it solved the problem.
I know that the best way to repair it, will be a circuit diagram/schematic, but I doubt someone has one.
the 13v lines would be the first to crush, but they seem to be ok. and all the other voltages seem to be ok, since everything else works.
I know also that salt water its the worst, but how on earth can I know where the other owner dropped the drone...
the boards came out looking pretty well after the cleaning.
I will replace a damaged misfit that I found on the board and give it another test after I refresh the firmware 2-3 times.
thank you for your time

Hello and good day brogdan. I am sorry for the troubles that you are having issues with your DJI Mavic Air. Since this issue is happening. It appears that this issue needs to be diagnosed by our team.  Just a
reminder the repair fee would depend on the warranty of the product. You can contact our support team to start up a repair case by using this link: https://www.dji.com/support. We hope to hear from you soon and looking forward to resolve this as soon as possible. Thank for your support.

DJI Stephen Posted at 3-23 08:50
Hello and good day brogdan. I am sorry for the troubles that you are having issues with your DJI Mavic Air. Since this issue is happening. It appears that this issue needs to be diagnosed by our team.  Just a
reminder the repair fee would depend on the warranty of the product. You can contact our support team to start up a repair case by using this link: https://www.dji.com/support. We hope to hear from you soon and looking forward to resolve this as soon as possible. Thank for your support.

I don’t think the mavic has warranty left, and i doubt you have any service center in Romania.

"I know that the best way to repair it, will be a circuit diagram/schematic, but I doubt someone has one."

Even then, without knowledge of what ICs do it could be fruitless.  Possible one or more ICs fizzled with dunking.  Good luck getting working ICs.

Hello brogdan, how is your process going, did you replace the esc board?

Hello, I recently got a a DJI Mavic 2 enterprise with the same issue and was looking to replace the esc/power board but didn’t know if it would fix it or not. Everything powers on an works fine camera works fine but get esc error when trying to take off.

I have confirmed that replacing the esc resolved my issue and should resolve yours to