Hi, I have a real problem with my BA XR8. Ater having new coolant tank, radiator cap and thermostat put in, woke up the next morning to a completely dead battery. Got a jump start, got a new battery, all good for rest of that day. Next morning, dead again. My mechanic came and jumped it and started no problem, took it to the shop, hooked it up and pulled bits and pieces off, checked the starter and alternator, and NOTHING! Now, it's at the auto elec, and still nothing. They are not finding anything at all wrong with the car.
It has an after market alarm which no one knew of and appears not even connected, and have had trouble with the door locks as in, remotes not working, and opening a specific back door unlocks all doors except the drivers side.
I understad there was a code for the ac compressor and an unknown that came up (the machine read, 'unknown code'). This is an absolute pain in the a**. PLEASE HELP!

Matey, this COULD be a PCM problem, this is located under the ICC unit.

Ok thank you. If that's the case, best option? Reflash or replace?
Also, the car was running hotter than normal for a good while, thermo replaced, twice, radiator unblocked and new coolant tank and cap, just in the past week. After unblocking it was good for a couple days then started getting hot again and exhaust emissions were rich.