Hi everyone.
After about a year of non-use, I took my Phantom 4 pro out of the box to make videos, but I immediately noticed problems. I put the Controller on charge which started to flash a white led. In the morning I found it off and when I turned it on without the cable attached it started to lamperiare the red led with a continuous beep.
The same battery charger perfectly charged the 2 batteries of the Phantom.
When I charge it, the Controller flashes the first white LED for minutes, then makes a blinking sound and then switches everything off.

So I tried to do the software update of the Phantom with Dji Assistant and DJI GO 4 but in both cases the firmware download stops at 91% and I can't do anything.

I have no solutions and I don't know what to do for this. I ask you for help please.

I try to upgrade without controller switch on but dosn't run. That's unbelievable because i have two problem at the same time and i can't upgrade controller and P4.
What can i do?

I'll echo this, in that I get the exact same result, when updating my P4P (from version 1.04); Errors-out at 91%. If trying to update the drone, via the controller, the 'Begin Update' button never becomes Enabled.

Chatted with support for an hour, but got nowhere. Perhaps there is a server issue? Maybe check back in a few days.

Thank you so much for your kind reply on the software. I don't know if it depends on a download problem ... I'll try again in a while. But I don't understand the Controller problem because it should be different.

fansd96b0eb8 Posted at 5-2 12:15
Thank you so much for your kind reply on the software. I don't know if it depends on a download problem ... I'll try again in a while. But I don't understand the Controller problem because it should be different.

I'm having the same problem, so please let me know if you find a solution. I will do the same. thanks.

I have the same problem. My P4 Pro dron was not used for a long time and my current FW version on the drone is V01.04.0602.
I have tryed to upgrade the FW from both - mobile app and DJI Assistant 2 and got the same result: Download stops on 90% - 91% and can't go further.

I have tryed to reset the drone to factory settings in DJI Assistant 2 - this went well and the reset finishes with no errors, but after that again the download of the new FW stops at 91% via the mobile app and on 90% via the DJI Assistant 2

Some update on the topic after my chat session with the support:  I don't think they undestood the problem and suggested to send the drone for repair.

I personaly don't agree with this because the drone is fully operational with the current firmware (in my case V01.04.0602). I think the problem is related to the download of the firmware itself or any other firmware curently since i have the same problem not only with the latest but also with the previouse upgrade. In fact i am not able to download the firmware ... not that i am not able to deploy the firmware upgrade on the drone itself.

I have tryed also reinstalling the mobile app and the DJI Assistant 2 app for PC and tryed again - same disspointing result - not able to dowload

Similar problem was discussed here: https://forum.dji.com/thread-181947-1-1.html