Here's my problem:
A Compaq's CQ40-627LA was working fine until one day it started to shut off as if the CPU were extremely hot. I cleaned the fan and the cooler, removed the old thermal paste and added some new one but the laptop kept shutting off after being on just for a couple of minutes. While I was trying to find what could be wrong I noticed that when I tried to turn on the laptop with the battery alone, the charging indicator LED blinked (telling me that there was no charge in the battery), and the laptop wouldn't start. Also noticed that when both, the adapter and the battery were plugged in, the laptop would go on for a minute or two and then off (just the way the problem started). And finally, noticed that when I tried to turn on the laptop just with the adapter, it wouldn't do anything, as if the adapter were dead. So I changed the adapter for a "known to be working" one, but the exact same thing happened: just the battery gave me the blinking LED, just the adapter gave me a dead laptop, and both of them gave me the charging indicator on (as if everything is ok) and two minutes of "not dead" laptop. Obviously I thought that the problem was the battery and got one that should be working (though I haven't verified that) because it is from an almost new laptop that had a MoBo problem. Anyway, with this "new" battery the laptop's always dead. No signs of charging or life at all.
I have already opened the laptop and verified the voltage at the internal DC jack connector, which seems to be right. The voltage that is missing is the one that should be present at the battery contact. So, my question basically is where (or what) should I be testing in order to find what's causing my problem?
Any comment would be extremely appreciated.
Thanks in advance.