Hi, my mother has a Macbook A1181 that has had several issues, and now will not start.

Current issue: Will not start when power button is pressed, nothing will turn on. No fan, no screen display, no sign that it is powering on at all.

When the top case is removed and the manual power switch is used (by crossing the two leads on the center of the logic board) the fan will turn on so long as the leads are crossed, but nothing else will turn on. The light on the front of the machine indicating that it is powered on will not turn on either. When the leads are uncrossed the fan will stop spinning.

Ruled out:
RAM issues (tried other ram, tried different combinations of current ram)
Top case/power button issues (will power on manually)
Hard disk drive issues (will power on manually without HDD installed)
Battery issues (powers on with AC power, battery taken out)
CD drive issues (powers on with drive disconnected)

I would very much appreciate any ideas on what the issue could be, or further tests that can be done. It is my guess that something has shorted on the logic board damaging it. If this is the case, then I assume that replacing the logic board would be a waste of time and effort, as generally they will just short again a few months after installation

Previous issues:
Replaced the keyboard/trackpad flex line connecting to mobo
Replaced HDD after failure
CDD does not work, has been removed
Machine has been dropped once before, hard enough to crack the case on the corner

Thank you for any help