I have the latest version of Assistant 2 for my Mavic 2 Pro. I connected my RC with a micro USB cable and check that my Internet connection is active. Started Assistant 2 and selected my controller. Clicked on Update firmware, and the progress bar confirms that the Update has been 100 % downloaded, and that my RC has been updated. When I re-start the RC and reboot Assistant 2, the firmware has NOT been updated at all.  I did this procedure about 6 times with the sane result. I also tried to upgrade with my CrystalSky hooked up to the RC. Each time I tried to upgrade, GO 4 warned me that the download failed - check your Internet connection. Tried this method a bunch of times as well without success. What a colossal drag. The final solution, which is NOT listed anywhere on DJI as far as I know, is to hook up my iPhone 6 to the RC and upgrade that way. Hazzah, it worked. The bonus is, the Mavic 2 Pro and its battery are upgraded at the same time. I'm a newbee for sure, so maybe I'm doing something wrong... but the instructions for new users are lacking from what I can see.

I've heard some people experienced this issue. It was solved by reinstalling DJI Assistant 2.

DJIJAKOB Posted at 11-23 07:56
I've heard some people experienced this issue. It was solved by reinstalling DJI Assistant 2.

Many thanks. I did re-install Assistant 2 but never tried to update the firmware with it. I'll try it next update.

For me updating through DJI GO 4 works best. Everything gets updated at once.

In order to help people, I would wish to see more details... DJI Assistant 2... ok, but which VERSION... the DJI GO 4 app... great... but... which version... etc.
But also if you run the latest version of DJI Assistent 2 on a Windows PC and which operation system... or on a computer based on Apple/Mac software and WHICH version.

I can only say, that I FIRST updated my Remote Controller of my Mavic 2 PRO using my PC (Windows 10) on which I already installed DJI Assistant 2 after a re-boot of my PC so that the NON DIGITAL SIGNED drivers could be installed...…. After that procedure my Remote Control had version 01.00.0200 (dd. 2018-10-22).
Then I connected my Mavic 2 to my computer and updated the aircraft also to version 01.00.0200 (dd. 2018-10-22).

After that I shut down my Aircraft and Remote, changed the battery and repeated the procedure... then the same procedure for my third battery.

Then I connected the Remote Control with my iPad 10.5" (iOS 12.1) and started the Remote... then DJI GO 4 and then the Aircraft (Mavic 2) and then I was able to check if every thing (also with all batteries) was at the latest firmware version...

All went well...

Had issues today with my M2P update. Powered everything up noting through DJI GO 4 I had 2 updates available, AC and RC. Clicked update and AC went without a hitch, but RC would not despite restarts etc... Tried via Assistant 2 and this failed also. Eventually tried reinstalling Assistant 2 and then RC updated. Powered everything back to be alerted of mismatch. Another update and all seems fine. Unfortunately with all the time lost the weather had turned to rain so not had chance to fly with updates as yet. Not had issues before updating via DJI GO 4, or Assistant 2, and hopefully no further problems.

Hi there, I appreciate your time to share your experience of your Mavic 2 Pro. If any case that none of this will work, I suggest you try to uninstall and reinstall the DJI Assistant 2 and retry to update. You may also try to change USB cables. Also, please make sure that Anti-Virus and Firewall are turned off on the PC. Make sure you are connected to a stable Wi-Fi connection for a successful firmware update. For reference, please watch the video tutorial below. Thank you.

CanonMax Posted at 11-23 09:34
In order to help people, I would wish to see more details... DJI Assistant 2... ok, but which VERSION... the DJI GO 4 app... great... but... which version... etc.
But also if you run the latest version of DJI Assistent 2 on a Windows PC and which operation system... or on a computer based on Apple/Mac software and WHICH version.

Hope this helps...

Assistant 2 v1.2.4 Mac
Go 4 v4.3.4 Mac iPhone 6 and v4.3.4 CrystalSky 7.8
Mavic 2 Pro firmware v01.00.0200
RC firmware v01.00.0200

I believe I've updated everything with the latest firmware.

RedWolf18 Posted at 11-23 09:37
Had issues today with my M2P update. Powered everything up noting through DJI GO 4 I had 2 updates available, AC and RC. Clicked update and AC went without a hitch, but RC would not despite restarts etc... Tried via Assistant 2 and this failed also. Eventually tried reinstalling Assistant 2 and then RC updated. Powered everything back to be alerted of mismatch. Another update and all seems fine. Unfortunately with all the time lost the weather had turned to rain so not had chance to fly with updates as yet. Not had issues before updating via DJI GO 4, or Assistant 2, and hopefully no further problems.

I had a similar experience.  Aircraft updated using DJIGo/iPhone, but controller would not.  I used Assistant 2 but it also did not seem to work.  The program would say successful but the firmware status screen would report the older version still current (yes I checked this after turning the controller off and back on again.
But just now I connected iPhone, conntroller and aircraft and DJI Go reports all systems normal.  This all seems a bit sketchy.  Not what I expected.

I had the same issue. I just updated on my computer, faster and better

What normally takes me about 10-20 mins took me about 2.5 hours. They were glitches on both DJI A2 and Go4 App. It kept giving me false 'current' updates or failed updates - I was beyond frustated; kept checking and nothing. Finally uninstalled both A2 and App and reinstalled. Updated craft and RC separately (prior both done simultaneously) and what you say, they both are on the current FW. Little patience and persistance goes a long way. I updated both on Mac LT via DJI A2.

Kept getting this frustrating message regularly.

"ASSISTANT 2 FOR MAVIC 2"      Should be displayed in the upper left hand corner of the window for ASSITANT

If not you may be using the incorrect version of Assistant....

Randy

For me, FW updates typically won't work with:
DJI Assistant 2 v1.2.4 (Mac and PC)
DJI Assistant 2 for Matrice 2.0.4 (Mac and PC)
DJI Go app on any Android device
DJI Go app on CrystalSky

But it usually works with an iPad Mini 4