HP Pavillion dv9730us notebook turns on for a few seconds with lights on the keyboard, & the fan attempts to run, but the machine then shuts down, and repeats this process. If I press "esc" during the sequence, the indicator lights stay on, but not the fan. During all this, there is a black screen, even with an external monitor. I have tried swapping out the two RAM modules in every combination, with no change. I have followed the recommended hard reset, with no difference. There are no beeps either. Anybody?