My son's Daiichi satnav/radio unit ,that came with the car when it was new, has died.

He has tried resetting it and had a Fiat garage take the unit out and check the fuse , but it fails to switch on.

The price for a brand new unit is disproportionate, and I read on the Fiat Forum that this unit is known to be unreliable.

I wonder if anyone who knows about auto electrics could advise me whether

1. The unit might be repairable- is there a common fault that usually causes this issue?

2.Would a replacement Fiat radio only fit directly into the units footprint which would be cheaper to source (possibly secondhand from a breakers yard) ?