If you can and are prepared to open it up, just give any connectors a push home. It's clearly not totally failed as you have had it working for periods of time. So something intermittent, like connectors or heat affected components. If its the connectors, its possible transport had an affect so would be fixed with the above.

Meridian owner since 1992
Prime & PSU, Focal Elear headphones, Roon (ROCK 8Gi5 NUC), Explorer 1 & 2, F80. 200/203, various Sonos (via Roon).