HP 8540w won't turn on

I just repasted the cpu and gpu in my HP 8540w. (This is not the computer in my sig. I also have a 8560w)

When I put it all back together and pressed the power button, nothing happened. All the media bar lights and status lights on the front of the laptop, blinked - and stayed blinking about once every 5 seconds.

I took the laptop apart again, reseated every cable, reseated the cpu, gpu, and ram, and made sure everything else looked ok.

Put it all back together again, and turned it on. This time it worked fine. Browsed the internet for a few hours, then turned it off.

When i turned it back on later in the day, I had the same problem as before. I tried reseating everything again, wiping the bios, etc, and still no luck.

Anyone have any idea whats going on? What do the blinking lights mean? Literally all the lights on the laptop blink at once every 5 seconds until I pull the power plug and take out the battery.

 

there is a documentation on hp notebooks error codes over here : HP Startup Menu Overview - HP Kundendienst (Deutschland - Deutsch)

click the "Blank Screen LED Error Codes" link.
alternate link : http://h20000.www2.hp.com/bizsuppor...21957&prodSeriesId=4096175&objectID=c01443366

i could not find a steady ( max 6x) blinking of all lights in this documentation. you should count how often those lights are blinking, is it really steady ( more than 6x) ?