My HP Pavillion Laptop has stopped booting. I only get the blue powerlights to flash briefly once. I have tried removing the battery, disconnecting the bios battery - all to no avail.

Following hp's troubleshooting guides, this points to a cpu failure - is it worth replacing the CPU (AMD) - or does the whole motherboard need replacing.

There have been huge issues with that series of HP laptops... I suggest you call HP and discuss the problem. HP has recently admitted some of these problems and has accommodated some owners with repairs, even out of warranty repairs.

It is my understanding that it is a motherboard problem, and the CPU is fine... but my info is all second hand... so call HP and be persistent.

hp had an extended warrentee, one or 2 years past date of purchase, for this specific problem due to defective mobos', usually overheating and damage of the gpu. Anyways, in this extended warrentee yes they will service for free, outside your out of luck.

Note that i had mine serviced, mobo replaced, and then a year later it died again, out of warrentee they offered me a 50% off service, ending up as $277. I bought a new board off ebay for $72 and spent 4 hours installing it, though this isn't for everyone...