I've had a failure along those lines. The machine would not reboot. I would see a "watchdog reset" error. The LCD was also out. I disconnected the LCD and the machine booted fine. A few weeks later the machine crashed with a "watchdog reset" and I replaced the LCD. The machine ran fine, for a while. By this time the machine wasn't in production anymore, we have moved on to a bigger machine. The problem occured with the LCD going out again. This time we could afford to keep the machine down for a while and we replaced the motherboard. That fixed the problem it seemed. We never had a "watchdog reset" again.
-Michael Cerda