When I removed my GM5 unit, and sent it away to have the central locking relays replaced, I had all the failures that you have experienced when driving the car without my cars GM5 unit fitted
Which to me sounds pretty bad, I'm no auto electrician but I'd check all the fuses, it sounds like the whole GM5 unit has failed,
surely it's more likely that the power supply to the unit has failed in someway.???
There are some larger fuses located behind/above the fusebox in the glovebox perhaps one of them has blown?