Open laptop, power on with black screen.

Tried rebooting by holding power button to shut down and pushing again to power on. Tried shift/F8 while powering on. Tried connecting external monitor (my display settings are set to allow another monitor). Voltage from A.C. adapter reads 19.36 DC. Battery was replaced with 10.8v about 4 months ago. I've also recently noticed that on waking up, the cmd prompt sceen is visible and would blink in and out, then go away after the laptop woke up. I'd type in my password and continue my work with no problems. Any suggestions?