Mother board

If you bought a motherboard, it should have had a new processor on it. The op system is Windows. If you have an install cd you can reinstall windows. This isn't a hardware problem. When there is a spill, if it is just plain water, it can be allowed to dry and usually be ok. If it is a liquid with sugar, that usually shorts everything out.

The motherboard is bad, you can try taking out the battery and only hooking up the Ac Adaptor to see if the problem goes away but if it doesn't then the motherboard they replaced it with is faulty.

Actually since water was spilled on it beforehand. Take out the hard drive and dvd drive and try powering it up again just to rule out the hard drive or dvd drive shorting out the computer.