Hi Dony,

First, check your memory, properly re-seat them, also if you have access to CPU - then you might as well re-seat them back, remove wifi card, remove battery ; just using your AC power adapter then power up the machine.   Usually, it could be just loose connection on some components. 

secondly, if the previous step did not work, then do a residual-power-cycle.  How to do this is:  remove your battery, remove your memory, remove any power connection to the systemboard. That mean NO POWER at all!!!  Now, press the power button for about 50 seconds so as to remove the excess power on the board.  After this step;  replace your memory,  and connect AC power adapter to the systemboard.  don't put battery yet at this time.  After the systemboard powers normally then shut down the system and replace the battery on the cradle.

Let me know what you get.

Good luck!

Michael

Hi Tom,

HP's and Compaq's have this switching circuit on the board that deliver signal to the inverter.  Please check the adjacent IC or transistor close to where you connect the data cable or the cable that goes to the inverter board.   If you are sure that your data cable is good then the culprit is the IC.  Im not so sure about availability of IC part locally, as some ICs are in-house and not retailed. If you can find similar motherboad that people sell in auction then that could be a good start to salvage parts.