B2: GPS/GNSS not working anymore

Ok, well that's good news then - your hardware is fine.

What you're seeing is that the GPS function has been overwritten by something. But I don't see any function containing return isGPSon anywhere in the BangleApps repository (assuming your apps were up to date)... So is it maybe something you wrote?

Could you try running this?

require("Storage").list().filter(f => require("Storage").read(f).includes("isGPSOn;"))

Hopefully it'll show the file that contains that code