I had the same issue with mine. I purchased a known used good one and bingo. it was half the price of a new one.
I took apart the old one but could not find the issue.
Sorry it is not the fix you were looking for but these clocks have been running since day one so it may have just died. VDO is located in North Holywood, Cali. You can send it to them for reconditioning but kind of far for you
