Samsung SR-S2029 – stops working if door open too long

Hello, this is an odd one, normally the appliance would sound a warning after door let open more than say one minute and restart once door closed. Now the display temperature remains unchanged (does not show temperature increasing) and the compressor cuts out. So when you close the door you think it is still working. Turning the appliance off at the wall, then on again reverts temperatures display to actual and everything starts working again. Possibly PCB fault? Appliance sometimes has to run off the standby generator when the mains fails, and even through I have surge filter in place the electronics could be getting some abuse. Any advice appreciated!