HP Elitebook. Wont boot even to Bios.

[SharkTank1]

EliteBook tries to boot, Caps lock key flashes every few seconds 4 or5 times total (4 times when using Winkey and B key and 5 times just using power button. I see now 5 times is "General System board failure and 4 times is gfx card failure), then the keyboard lights go out, fans kick in on high, black screen remains, and will run like that forever. Other buttons (wifi, speakers etc) have lights on but no keyboard lights.

Caps lock blink indicates a power or heat issue though the power  supply and battery check out fine. It just had a complete airway cleaning and was running very very well in that department.

Have done a reset (unplugged power and battery and held down power for up  to 2 min)

Have tried forcing a bios reset (Win key and B key)

Have tried forcing to external monitor (F4 and Function key)

Have tried booting from another drive (swapped drives and have put an OS install USB flash drive in)

Have reset RAM

Have tried resetting the CMOS where the BIOS is stored (WinKey + Vkey on power up)

Have made a BIOS USB recovery disk -  while the usb device lights up on reboot it does not do its thing (even with a WinKey + 8Key on power up). Computer remains on black screen with fans on high.

Have tried prompting the BIOS to show up but no dice. (on boot - escape, F8 through F12 -  the usual suspects)

Unit was working normally 10 hours earlier, and was shut down normally. However the night before it was doing some heavy lifting. Airways were recently cleaned so it was throttling the fans correctly with excellent flow and raised up to allow best flow possible. Is there a thermal fuse that could have blown? Is that resetable? It could be on either the GPU (Nvidia 3000M) or the motherboard. Or does the 5 Caps Lock blinks means the mother board is cooked? Even though it was working just fine 10 hours earlier? Did turning it off kill it?

This all started with adding another internal drive, installing Win 10 on that drive and then creating  dual boot with both Win 7 and Win 10 (each on a separate drive). That all worked fine, inlcuding the dual boot, but Win 10 stretched its fingers into the Win 7 drive and messed up all sorts of settings. Been spending the week sorting those out.

Last night I found another corrupted app and was trying to deinstall it. After two hours, I just left it running and in the morning that deinstall had only reached 54% (its a monster of a program but still!). During that period it was throttling the fans for cooling but never reached the peaks I am hearing now on the blackscreen reboot so I don't think it was ever running at max heat otherwise the fan would have gone into overdrive. Yes it was running higher than idle as you would expect but not stupid crazy. In the morning I killed the deinstall and rebooted. Deinstall fired itself back up after the boot up. I killed it again, and used the machine for about an hour: no problems. Shut down normally, unplugged the power to save the battery as I always do. When I came back 10 hours later it woudln't even boot to the bios as described above.