I'm looking at this HP M6 for a friend's daughter to see if it's salvageable...it was dropped on a corner and damaged extensively...as it's not a cheap machine (Ivy Bridge Core i5, 1TB HD, 8GB RAM, aluminum lid, fingerprint reader, etc. & especially Win 7, not 8.1) it might be worth it...
The LCD internal glass was cracked, hinges broken loose from plastic (lid & case bottom need to be replaced), all the internal display showed were horizontal & vertical lines and the cracked glass in one corner...to see if the video/motherboard was still working, I temporarily connected it to an HDMI port on a HDTV & initially it showed a flawless image & booted to the Win 7 logon screen...when I asked it to reboot after it finished applying some Windows Updates (ah, Windows...) nothing came up on the HDTV (pressing F4 or Fn+F4 did nothing).
As I'd need to break it down anyway, I disassembled down to the motherboard (yes, observing static precautions) & removed the internal video cable to see if that was shorting out the video (Doh!)...I reassembled the power button on palm rest/cover, installed one SODIMM & the keyboard, then the battery pack, still no video on either the VGA port or the HDMI...I've tried booting from the DC power supply w/ no battery pack installed (hard restart), I even tried reinstalling a backup copy of BIOS from the HP Recovery partition (Windows logo key + B, then 1 second power button push, which ramped the cooling fan to high and set the Caps Lock LED flashing, so I assume it re-flashed the BIOS - as was suggested on a HP troubleshooting page), but still no video, though the machine stayed running (but no beeps (speakers are connected))...obviously, reattaching the hard drive made no difference.
In desperation, I reconnected the internal video/webcam cable & tried to power up, now the backlight flashes briefly, cooling fan spins for 5 seconds, then stops, power LED & Wi-FI light (orange) remain lit, but nothing else.
Anyone have any ideas? Is the motherboard fried?