I have same problem power light flickers with or with out battery , when i does boot up for all of two seconds it claims cmos using default settings then shuts off immediately - I will reply with any findings. But from other forums they claim motherboard fried .
I have a Compaq Presario C500 laptop with Vista. Sometimes it will boot to the CMOS screen but it shows that the CMOS info has been reset like it would if the CMOS battery was dead. It will stay on for a few seconds and then lose power. The little power lightning bolt on the front will flash quickly. I have tried removing the battery and just hooked it up to the charger and when I do that the power button light flashes quickly. I tried another charger to make sure that wasn't the problem. ANY help you might offer will be greatly appreciated.