[Baron Munchausen]

You would have to actually be doing something to overheat the CPU. The newer CPUs are quite smart and turn off parts of themselves that are not being used. So, they only overheat under a full load. If the CPU was working when you took it out of the previous system, it should be fine now.

Pulling the CMOS battery was your last option. If they left something set in the BIOS from when it was in another system, that should have cleared it. How long did you wait, btw? At least 20 minutes?

If that didn't work, there's no reasonable way you could rescue this board without being an Asus tech with lots of fancy equipment.

Pretty low of them to not have a serial number on the board. This must be a sneaky way of terminating support without having to own up to it. But the core 2 Duo is still a relatively current CPU and there should be plenty of boards for sale that can use one. Go to a good site like NewEgg and start shopping for a MB that says it handles your CPU. The specs are almost always available in a link on the item page. It'll probably cost $100 or so. But then you could re-use all those other parts.