Hi, Pretty sure your rear door modules either DCM3 or DCM4 or both will be dragging down the CAN bus creating problems with radio and IR. this wont show up with diagnostics.

When it faults next disconnect DCM3 or 4 one by one and see how the key system reacts.

Always reinstate the water barrier protection on the doors, use ados contact adhesive or similar.

Very common fault on 98+ 202