Hi there,
Take a look at the clock battery surroundings,and see if you notice any leakage from the battery. Any corrosion can destroy the board. These boards are multilayered, and the acid from the battery leakage can get in the inner layers of the board and blow all out.
Would be even better to check the battery voltage with and multimeter. If it's below the 2.3V border, just replace it.
Besides the battery problem, you can have a "cold soldering" (as we technicians knows it here in Brazil) problem. Some of the solderings can be loose or cracked. So if you do have an AC isolated soldering iron, you should try to patiently resoolder everything you can reach.
Right now these are the things that comes to mind for your problem.
Good Luck, and sorry for my bad english.
Marcelo Pires.
