OK people I have a friends laptop which won't post. If the charger and laptop battery are connected at the same time, the laptop tries to boot but can't and gets stuck in a cycle. The power lights on the laptop come on and the fan starts, but after a couple of seconds they go off and will not post to bios. I have checked the mobo and have replaced the mobo CR2032 battery which had some rust on it, but this has changed nothing. I have checked the other components but can't detect anything obvious. No beep codes can be heard. The laptop was bought in 2008 so is out of warranty. Any ideas?
What happens if the battery is taken out of the equation? Some laptop batteries degrade to the point that the laptop won't switch on with it installed, time for a new battery.
No difference, it still tries to boot by itself but can't and gets stuck in a loop without posting to bios...
when you changed the cr2032 did you try leaving it out for a while? to be honest it does sound toast though, especially as it's not giving you any beep codes at all.
I've fixed some weird things in the past by pulling all power and the cmos battery for 20 minutes, seems to work when a cmos reset fails. Otherwise pull out and reseat everything. If that fails unplug stuff until you reach a point that you get post.
If you're feeling adventurous you can disassemble the entire laptop and try to boot the thing with the motherboard outside the case. That will mitigate unusual problems such as an errant paper-clip shorting the motherboard etc. Don't laugh, I've fixed a "dead" laptop by removing a staple from the motherboard before now - it happens.