I've installed Visual Studio Code and nrfutil and nRF Connect and J-Link and managed to compile Blinky and flash the Thingy:91 X using the terminal:
./nrfutil device program --firmware build\dfu_application.zip --serial-number 85530168C83B32B7 --traits mcuboot --x-family nrf91 --core Application
Now, however, the two com ports don't show up again, and if I try powering up as mcuboot com port, I get errors:
[00:00:00] ------ 0% [85530168C83B32B7] Failed, [mcuBoot] Manifest does not contain supported SoC for multi-image update
Error: One or more program tasks failed:
* 85530168C83B32B7: [mcuBoot] Manifest does not contain supported SoC for multi-image update (Argument)
If I try and just program a .hex file I get:
[mcuBoot] Programming of Thingy:91 X requires a target when firmware is in HEX or BIN format. (Argument)
...and nRF Connect "Quick Start" doesn't see the board now
https://hello.nrfcloud.com/device/ still connects and interacts with the device ok
Please give me a hint on how to get my board back to square one........
Scott