Could someone PLEASE help with Devo 8s?

2 questions:
1) can you get into programming mode (EXT button while power-up)?
2) can you get into USB mode (ENT button while power up)?

If (1) works, and (2) works, then something is wrong with the filesystem
If (1) works, and (2) does not, something is wrong with the firmware
If neither (1) nor (2) works, something is wrong with the hardware or bootloader.

That is a bad sign. It implies the bootloader is corrupted or there is some other hardware failure. If you are sure your battery is ok, it likely means you'll need to replace the bootloader. It should be possible to do this with a $4 cable, though I haven't done it that way myself yet. I need to experiment on my Tx to verify it works as I expect.
I'm not sure how an upgrade could have broken your bootloader though. The TX has protections to prevent that from happening.

I need to check it first, but basically you'll likely need:
2 2-pin jumpers
a 1/8" phono jack
a CP2102 USB to UART (search CP2102 on ebay)

The procedure is not very challenging. The hardest part is connecting the phono jack to the CP2103 module.

Alternatively I can (very likely) fix it for you, but you'd need to get it to me which may not be reasonable depending on your location.

FYI, I did just double check that nothing is wrong with the v2.1.1 dfu file.
It is theoretically possible that something like a non-shielded USB cable would cause bad things to happen. I've had real problems with my 3d printer using a non-shielded usb cable (no magnetic core on the end). turning on the lights would cause an error in transmission. That said, I've never seen anything like it with the Devo. I don't use a shielded cable for my Devo, and have flashed it hundreds of times.

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