I have a Gateway M6846 Laptop that will not post. I've tried taking out the battery and using the power cord. I get lights, fan and the hard drive spins, but nothing on the screen. no setup options, etc. Plugged in an external monitor, to see if the laptop monitor was bad, but it made no difference. I tried rebooting with a system disk, nothing. The hard drive was removed and checked on another computer. It appears okay. Any suggestions?