Phone dead (Dont turn on, pc wotn recognize it)

Hi guys, my little cousin have this phone and ive been tweaking it for him since he bought it like year and a half ago. Th phone was on CM11 with the mount sd script and it was working fine. Now suddenly stopped turning on. My cousin says he was charging the phone being off and that it reached 100% in about 30 minutes what it was weird he says. He unplugged the phone and now it dosen't tur on, the pc dont make any sound when is plugget into it nor shows anything in the Windows device administrator, the charger don't make the screen turn on. I tried 2 cables and 2 chargers. I think that the board got fried maybe a electrical fucltuation in his house, an overvoltage, dont know how you guys call it, we're from venezuela. Any help or explanation will be welcome.

Sorry for my english.