if it's just resting it could be anything from a I.C. that needs to be reseated to a problem with the power supply or a bad connection.
you will need to unplug and visually inspect each of the larger plugs (I.E. not the ribbon cables) for heat damage. you will also need to do some tests with the multimeter to find out if it is a low 5 volt issue.
If it is a slam tilt then thats a whole different scenario, try triggering the slam tilt with the slam tilt switch and see if it just resets or if it gives you some indication that the slam tilt has been triggered.
