well this happends 1/1000 of psvita but still it happens.
the only real fix for that is to bring it to sony and have them deal with it, or you can just buy a another vita 1000 series board over the ebay or alibaba or something....
although most of the vita fat boards sold in alibaba are 3.60 or below firmware installed on it, so if youre interested on the henkaku/enso thing, this might be your chance.