[Closed] Garmin 800 help - not retaining settings

My Garmin 800 crashed mid-ride a week or 2 back. Failed to restart properly even after a charge, however my other half who has more patience with these things than me managed to persuade it back to life. It now connects to Garmin Connect OK, and says it's up to date but lost a bunch of the most recent rides.

The big issue is that it loses all bike and rider info every time its turned off and it won't pair with the sensors on either of my bikes (although the HR monitor connects fine). My googlefu is being weak at the mo, so any ideas?

Thanks

J