Many thanks @WTFDproject, seems like Mitchell's might be the ultimate solution. But before doing that, I may still wanna try something else. My idea is to change version to a higher number, like V1.28 or something, so it will force the hardware to take the firmware. I don't know if it makes sense to you?All I can offer is a little progress report. I now have a functioning black/box IMU CGo3+ to work with. And had some limited success in duplicating the failure. Installing version 1.25 did kill the gimbal, but it did not produce any beep codes. I also did not find a way to restore version 1.27 using only software available to the general public.
You mentioned not finding a copy of the 1.27 firmware. It is available on John Mitchells Yuneec Skins website, but the firmware itself will not load by itself. I believe it has to be part of an upgrade package that has the needed bootloader software built in. Since there were no later versions made available after the initial version 1.27, there is no upgrade package. I spent a lot of time trying to replace the version 1.25 firmware in the latest upgrade package with the 1.27 firmware. It looks real good but so far doesn't work at all. Will work more on it.
You may wind up sending the camera for repair anyway. I know John Mitchell's shop can do the work. Some other shops, such as Vertigo Drones may also have everything that is needed.
John can be contacted at:
CGO3+ Camera Repair Estimate Service. - Shipping Instructions (see Photos): Find a Box Approximately: 8" x 6" x 5". Only Ship your Camera and Camera Cover/Lock, Including All Broken and/or Detached Pieces of Camera. Do Not Include Memory Cards, Cables, Lens Filters or Accessories they will not...yuneecskins.com