Won't power on even after replacing logic board.

Its possible that it could be a problem with the topcase, you could attempt to power on the computer from the jump switch on the board.. there are 2 solder points that can be bridged with a screwdriver, if the unit powers on, then you know that the power button on the topcase is no good.

I circled in red the logic board power button for this model in the picture, I find a t8 driver does the job very well.

I have a feeling it's the power supply.

Hi Shaolin,

The PRAM battery should have 3.0 Volts, that means that its correct. (When these kind of batteries are "dead" they start having less than 3.0, like 2.6....).

The bettery is used the "retain" your configuration for (startup sound volume, startup Screen light level, etc...) Without the battery these values would be erased after restarting your MB.

Hope it helps you

Recheck your adapter output voltage using volt-meter and check the spec of adapter on their label. If the output too below (<< 19 volts)dan not enough currents deliver to logic board. Or the adapter cable is half-crack (just small amount of current-Ampere can through via the cable). Try use another adapter. Other reason maybe the CPU fitted not properly, don't tide CPU's skrews hardly.

How many people have this problem?

http://www.youtube.com/watch?v=9CUJTXoSx...

This is not my video but it's the same symptoms I'm getting, I have tried Removing and re-seating the ram, I have changed the ram with a new set, I have removed the hard drive and installed a new one and still gives same symptoms..

I also removed the hard drive and tried it with out the hard drive to see if it beeps, I have tried it with out the ram to see if it beeps.. and nothing.. all same results..

Tried different power supplies... tried just ac tried just batter all same results..

Mine is a a1260 2.4