W580i problem

My girlfriends W580i intermittently keeps humming or vibrating even when the phone is switched off. The reason I say humming or vibrating is because I can't get to the phone as she is living 6000 miles away in South Africa. Not much of a boyfriend hey. Joking apart has anyone come across this problem and if so what do we need to do to rectify this please.
I assume it's probably the little vibrating motor most likely earthing but although I'm ok with most electronics mobiles aren't really my area

it maybe a hard were fault has it had any water damge and some point