Thermal issues can be found by spraying the suspected component with freeze-it.
Chemtronics Freeze Sprays
Or a similar product. Use your finger to narrow the suspects down then hit that area with a short blast. Unit come back alive? You may have to spray, power down and then back up incase there is a lock-out or foldback mechanism at work. Processor detects a fault condition then locks out operation or the power supply detects over current then folds back the current .