Hi @somgud ,

Sorry, without a schematic of the motherboard (systemboard) circuitry it is very difficult to be specific about where the problem might be.

Getting the power light to blink red indicates that at least power is getting somewhere into the laptop. Whether all the separate power rails for the various different voltage supplies required within the laptop itself are OK is a different matter.

Given the age of the laptop (is it nearly 10 years old?), it is easier to replace the motherboard.

Here is a link to the service manual. Click on the systemboard assembly link in the Contents page to view the necessary pre-requisite steps and then the procedure to remove the systemboard.

Hopefully this is of some help