sw26

So I bought a Sony MZN510 player from Amazon last May (I'm in the UK), and I accidentally dropped the unit a couple of months later, from the chair I was sitting on. Ever since, when I open the unit, there is a strange high pitched hiss that only lasts about a second, but it does this when there is already a disc in and I press the play or menu buttons to turn the unit on as well. Anyone know what this is? Thanks