Thank you in advance for anyone who can help. I have a laptop that my niece was given, and she has used for a year or so. It stopped working and they sent it my way. Based on the issue and the LED above the power jack I surmised that the system board was faulty. I ordered a replacement off eBay and after making the swap I am getting the same issue. The unit will not boot. I get a single white LED flash when the power supply is connected. 8 amber flashes when the power button is pressed.
Specs: HP Probook 4525s with apparent water damage inside the case. (One reason I started with the system board, plus the lights code from the power jack and a quick google search.)
Troubleshooting: I have tested the power supply with an OHM meter. Removed the previous system board part# 613211-001 and replaced with one that I was assured came from a working unit. *Fingers crossed that is right.* I have removed the battery pack, hard drive, wifi module and the optical drive to try to get it to boot to BIOS. Replaced the CMOS Battery.
Any advice is appreciated.