HP pavilion dv 6700

I have a friends laptop that when you turned it on 3 seconds it goes off then about 6 seconds it turns on and cycles His battery was dead so I charged it. when you have it on battery it shuts off and starts constantly, You cannot turn it off by holding on button. I took it all the way down to mother board found cpu fan assembly plugged with nicotine and hair and dirt. flushed clean Reassembled and tried it same scenario Removed bios battery for around 20 minutes then reinstalled tried operation DEAD Will not turn on now.Power cable lights blue light around cable and charging light goes on. Help please.

 

I have found on another forum I need mother board