As all the pies mentioned, turn it off, then on again. There may be info on the start up screen…
I did this last time it was mentioned on here. Saved me a big bill buying a replacement for my 800 once already! I took it off at the top of Cwmcarn to adjust the headset and forgot to put it back on. Got back to the car before I realised so was just about to set off up the road to fetch it. Checked my phone (which was in the car, carry an old Nokia brick for emergencies) and there was a text saying someone had found it. Sent one back to say I was in the car park and a guy rode up to me 5 minutes later and handed it to me. Offered him a few quid to buy beer/coffee/Maccy D’s and he wouldn’t have it. Big thanks to a random up visiting from Bristol 🙂