Have you dismantled the laptop to see if there is anything obviously wrong inside? If unlikely, maybe a RAM stick has dislodged or something, and that is preventing POST. Maybe even the CPU fan, as most computers wont boot if it cant find one, to prevent damage to the CPU.
Do you have a replacement battery that is known to be good? Swapping that in will either fix the problem or at least tell you the existing battery isn't at fault.
Other than that, no idea. If worst comes to worst and its unfixable, remove the HDD so you can give that to the customer, so at least they can pull any data they want off it.
I was going to do all the reseating, but thought I'd ask away before doing that. Anyways, I did that and wierd enough, theres a green light on the machine now instead of red. Maybe I've had it plugged in long enough for a red light to turn green.
Also maybe I will check dealextreme for some type of a battery thats universal.
Have you heard of a universal battery? I have ordered a universal laptop ac about a week ago.
But it's obviously not really worth it for me to order a battery for every laptop I encounter. I have 7 laptops here I've collected over time, most about a min pentium 4, various brands, and never of the batteries are interchangable. The voltages and amps are quite +3 / -3 voltages different, even the connectors have more slot/pins and the location of the connectors, varys computer to computer.
Do I absolutely need a battery to see if it will boot up. Even my oldest laptop 11 years old, can boot with no battery only AC.