So here's my problem.
My AC and RC connect all good but my DJI Go app doesn't recognize the AC.
Every time I start everything up it only says in the bottom left "RC Connected"
I can fly with the Phantom but there's no video or information from the AC in the app.
I believe this is a problem in firmware version in the controller but I just can't get past 2% in updating the controller.
I have tried with four different units and about five or six different cables. (2 iPads were one is brand new and two Android phones were one is the latest Sony XZ)

Every try stops at 2% and after that it says update failed.

I'm panicking here, what the heck can I do?

Oh, I have tried with both sd card in phantom and without.

This may help!

Try not start the DJI GO app before starting AC and RC. even don't connect your mobile.

First restart your device.

Second, turn on the AC then turn on the RC.

After connect the cable to the mobile and open the DJI GO app.

End!

One more thing I forgot to say!

At "aircraft status" in the dji go app you can see if RC needs update so tap the "overall status" and you can download and install the needed updates.

Tested it all just now (again).
Still no luck. Stucks at 2%

Bumping my own thread...
Still haven't figured this out. Been doing somewhere in the hundreds of tries but that dang thing just won't accept the update, or downgrade either for that matter.

I need help I have a phantom 4 and have not flow for a while and I can get it to do anything or update firmware

Will it hurt to delete my app and start over like I am just starting to fly my drone?

What's the current firmware of your drone and controller? Matched firmware is required. Please make sure there is solid internet and try again. If still no helps, please send it in for fully diagnosis: http://www.dji.com/support.

fans502f0b42 Posted at 2017-9-17 10:02
I need help I have a phantom 4 and have not flow for a while and I can get it to do anything or update firmware

I'm not quite understand your point. Is there any error message when you start the drone, connect the controller and APP? If not, do not worry.

The latest firmware thru DJI Assistant 2 on the Phantom 4 and 1.8.0 is what I belive the controller is on.
I've tried up/downgrading thru the DJI GO app several times and never get passed 2% but the version info says either 1.5.80, 1.6.0 or 1.8.0 depending on which one I try switching to.
When trying to upgrade through the "app" and not through downgrade option it says 1.9.2 and when it fails at 2% again then it stops asking for updates but it never works with the drone.

The led turns gren on controller and I can fly the bird as normal but it won't recognize the Phantom in the app. It only says RC Connected in the bottom left corner when starting up the app.

I have the same issue as 9# . I have a Phantom 4 that I haven't flown in a while. In that time you have removed the P4 from the old DJI Go app and added it to a new DJI Go 4 app. The AC and RC worked absolutely fine before now the DJI Go 4 app (latest version) constantly shows a grey disconnected sign. The AC has new firmware to update but when I connect the AC to my PC using ethernet connection the upgrade downloads but then sticks at 'transmitting' and never gets to 'upload'. The DJI advice online is to contact DJI Support after repeated failures, BUT DJI Support just constantly refer you back to the website - quoting do you have the up to date versions. The answer is YES to all. You also ask me to pay to send my AC across Europe for it to be fixed...… It is NOT broken, it a software issue manufactured by DJI.  Please provide answers to your customers who have already purchased expensive AC, instead of forging ahead and developing new products that are now impacting on earlier models. From what I gather off the Internet this is now a major problem that DJI need to fix at their own expense and quickly before it goes viral and tarnishes what are actually excellent AC - When they FLY.

fans2c1f7d00 Posted at 6-9 08:42
I have the same issue as 9# . I have a Phantom 4 that I haven't flown in a while. In that time you have removed the P4 from the old DJI Go app and added it to a new DJI Go 4 app. The AC and RC worked absolutely fine before now the DJI Go 4 app (latest version) constantly shows a grey disconnected sign. The AC has new firmware to update but when I connect the AC to my PC using ethernet connection the upgrade downloads but then sticks at 'transmitting' and never gets to 'upload'. The DJI advice online is to contact DJI Support after repeated failures, BUT DJI Support just constantly refer you back to the website - quoting do you have the up to date versions. The answer is YES to all. You also ask me to pay to send my AC across Europe for it to be fixed...… It is NOT broken, it a software issue manufactured by DJI.  Please provide answers to your customers who have already purchased expensive AC, instead of forging ahead and developing new products that are now impacting on earlier models. From what I gather off the Internet this is now a major problem that DJI need to fix at their own expense and quickly before it goes viral and tarnishes what are actually excellent AC - When they FLY.

I forgot to add - if these were cars the manufacturer would be forced to make a recall and repair them.

fans2c1f7d00 Posted at 6-9 08:42
I have the same issue as 9# . I have a Phantom 4 that I haven't flown in a while. In that time you have removed the P4 from the old DJI Go app and added it to a new DJI Go 4 app. The AC and RC worked absolutely fine before now the DJI Go 4 app (latest version) constantly shows a grey disconnected sign. The AC has new firmware to update but when I connect the AC to my PC using ethernet connection the upgrade downloads but then sticks at 'transmitting' and never gets to 'upload'. The DJI advice online is to contact DJI Support after repeated failures, BUT DJI Support just constantly refer you back to the website - quoting do you have the up to date versions. The answer is YES to all. You also ask me to pay to send my AC across Europe for it to be fixed...… It is NOT broken, it a software issue manufactured by DJI.  Please provide answers to your customers who have already purchased expensive AC, instead of forging ahead and developing new products that are now impacting on earlier models. From what I gather off the Internet this is now a major problem that DJI need to fix at their own expense and quickly before it goes viral and tarnishes what are actually excellent AC - When they FLY.

Try a different USB lead to connect PC to P4. It would seem that it has downloaded file to PC from DJI server, but is unable to forward that file to the aircraft (that's the transmit).
You will also need to ensure that RC is at version V1.9.3 otherwise there will be problems with the RC communicating with the aircraft when its firmware is updated.