Bluetooth dying

Argh, sorry to hear that. Does pinching the screen hard in the top right corner help at all? Sometimes that makes it work...

There are two possibilities:

• The aerial is part of the case, and it connects to the PCB via a little sprung terminal in the top right edge - it's possible that this has lost contact, in which case pinching a bit may clear off corrosion and fix it. Or you could open the case, unscrew the PCB and screw it back and that might fix it.
  
• The actual microcontroller has come slightly unsoldered (it's BGA). I'm not sure on what tools you have, but if you have a hotplate and flux then the fix may not be too difficult - but again it requires opening the case, then pulling off the battery - and you can't easily use hot air because you might melt the GPS aerial.
  
  

I think actual microcontroller damage is unlikely so it's probably one of those two things. I guess if it's not usable right now then opening it, taking the PCB out and putting it back is worth a try.