I may be “a bit” late, but for the records if anyone has problems with corrupted firmware:
I bought a defect Throttle Quadrant on purpose on ebay for a few bucks to give a repair a try. The device was not detected at all on USB.
Solution:
before plugging in, push both buttons in front of the engine switches, hold them, and connect the device. As a result, you should hear the normal USB connection beep from windows. The device shows up in device manager and also is recognized in the Thrustmaster firmware update utility marked in [BOOT] Mode. Now flash the firmware - and have fun 
Probably this also works with the sidesticks, but I didn’t try to find out the needed buttons yet.
Best regards
Marcus