Bios-Motherboard or HHD problem? laptop not responding

Hi everyone.
4 days ago, my laptop dv7 3165ev W7 Home Premium, just stop responds to everything. Touchpad works by itself, keyboard stops and starts working, touch keys of sound, wireless and bluethooth the same, sounds increase-decrease without touching anything, time is changing, no matter if I change it from BIOS or from windows clock. I can't see the WLAN connection. The diagnostic test seem that the HHD is ok and memory also. I changed the little 3volt battery but nothing. I restore my pc nothing again. I format HHD with W7 ultimate but nothing again. The only problem is that laptop doesn't have battery.
Does someone know anything about that?
Thank you!