ruuvitag GATT services

Have you tried just reflashing using the firmware update mode (maybe to a Ruuvitag firmware) and then flashing back to Espruino?

Yes, I tried flashing both Ruuvitag firmware and Espruino but it fails in both cases.
I also have the Ruuvi DevKit but I can't use that because a pin is missing because of some soldering... the only way to flash it is through Bluetooth.

Have you tried turning bluetooth off and on on your PC? GATT ERROR might be due to the computer itself getting confused.

I tried, but my laptop can't see the Ruuvi. I get the same error when I try to connect with the nRF app and when I try to flash in bootloader mode. Seems like something's broken in the GATT protocol because the Ruuvi Bluetooth is not working anymore.