Hi. Just received a used PC. It's a Dell, an old one its running windows 2000. I cant get it to boot. There is a rapidly blinking LED button at the front of the case, Voltage is correctly set. If I switch the mains off and on again the fan occasionally starts, remains on for a second or so, then cuts out, It has an odd PC case. At the top rear of the case there's an eliptical recessed button. Is this the power button, or does it open the case? The unit was driven in a van for 160 miles. its possible something is loose, but i cant work out how to open the case! Help!