Thanks for suggesting re-typing it but that’s the first thing I tried, the unit doesn't seem to hold the settings the next time it boots up it just continues to cycle through displaying "Meridian 861" then switching off.

The PSU hasn't been upgraded so maybe it could be related to that.

I will probably just sell it as spares if I can't find anyone to repair in the UK.

Hifi - PC, 861, 2x505, XTZ
Cans - PC, Oppo HA-1, Fostex TH-X00PH