HP 9700 Power panel on off Loop

I have an HP 9700 Laptop, that has a power on/off loop. The panel lights will come one then 3 seconds go off over and over. I tried another power cord and also another battery but problem still exist. I bought this laptop in 2008. I have bought 3 new cords already this year. This one was just about to go again, because it would sometimes go on battery.
Has anyone had this problem and can identify what area for me to look at next?
I think it maybe electrical of some sort but not sure. I read elsewhere there were mother board problems with this pc. It is out of warrently so I either have to fix it myself or send it out.
I would appreciate any help!
Thanks
Verna

 

Hi. have the same problem with my dv9700. Temporary fix is to remove battery, unplug & hold down power button for 60 secs. after just pop in the battery, plug it in & turn it on. works for a while & goes back to the cycle. have been googling a perm solution for months - no luck.