Hi, My central locking will no longer work from the two button key. I have done the old "turn key in doorlock three times til the light on the door comes on, then hold down lock and press unlock three times" method several times in the past and has always worked. But now when I do it the led on the door just stays lit (still goes off after about 10 seconds)instead of flashing, but the led on the key still flashes ok so I think the batteries must still be ok (although I have not changed them) so the remote does not now work. I can still lock manually using the door lock. I would be grateful for suggestions. Thanks.