I updated Thingy:52 to firmware version 2.2.0 using the Thingy:52 Android app.
WIth the Thingy:52 running v2.2.0, the WebApp for Thingy:52 can pair with Thingy:52 but it then throws up an error message:

Firmware update required!
Using the WebApp I tried to revert to v2.1.0 and v2.0.0 but the DFU fails.
I also tried using the Android app to install firmware application-only package file: thingydfupkgappyv210HW10.zip . It enabled the bootloader and failed with a "FW version failure" error message.
We're dead in the water until we hear from you.
Len Moskowitz ([email protected])