This happened to me. In the end it defrosted.Had to change pcb,which is really easy to do. A fitter did it 4 years ago,I did it 2 weeks ago but it costs £62 with postage from Whitegoods.Take off plastic cover, top front of freezer (turn front feet down to get freezer out!) undo 2 connecters,slip thermo-control out, slide old pcb out, slide new one in reconnect! Simple! Make sure the power is switched off first lol. Oh yeh! the new pcb looks different to old one but works fine.
Andy
September 2009