Engine Repair Fault

My 2015 DS5 randomly powered down in traffic.

i’ve not been able to start it since and when it had power it would go into Economy mode and the fauly message would say Engine Repair fault. The serivce light and engine manage lights also come up on the dash. The recovery people initially thought it was a battery issue the battery fine it seems its an issue with the ECU

Any suggestions

When plugging in via OBD2, do you get any error codes?