It will not turn on at all, meaning you see absolutely zero indication that their is some kind of activity? No vibrant logo? Nothing?
Can you get into recovery mode? Download mode?
See if you can get into download mode.
Hold down both power buttons, meaning hold down the up and down key at the same time, never letting go. Grab your usb cable attached to your computer, and plug it into the phone while you still hold down both volume keys. Does the phone go into download mode?
http://androidforums.com/vibrant-tips-tricks/177526-how-enter-download-mode-what-worked-me.html
http://androidforums.com/vibrant-tips-tricks/177458-how-enter-recovery-mode-correct-procedure.html
Hopefully you don't have one of the phones with the 3 button issue.