Hello! My laptop started having this issue during my upgrade from Windows 7 to Windows 10. I did a lot of searching, but couldn't get very far so I'd really appreciate your help on it! For example, I'd much rather buy a bios chip programmer for a few dollars and spend a few days on fixing this up instead of buying a new computer, but I don't know if we're way past that point, or if that's even the issue.
When I turn on my PC, I see nothing on the screen. I don't even think the laptop screen turns on. The keyboard backlights work, and I get the power light and caps lock light. Then my computer just restarts in 15-30 seconds. This repeats constantly and I can turn off the laptop by pressing the power button (I don't have to hold down the power button like it requires when windows has loaded up).=What I tried to fix it=
Try an external monitor to see if issue was related to the laptop screen.
Start it without anything plugged in to the USB ports, and no HDD, RAM, and ODD (tried many combinations of this to isolate the cause).
Take out battery and unplug and hold down power button for a minute.
Take out battery and unplug and leave it like this overnight.
Take out CMOS battery, laptop battery, unplug and leave overnight.
Short JRST2001 and JRST2002
(doing this stopped the auto-rebooting and I now need to hold down the power button the turn off the computer. Additionally it made it so my PC turns on the second I plug it in)
Hold down CTRL-Home during boot with HDD and a USB stick with G75VW.bin (no light on USB on any USB port)
I may have made mistakes during these fixes (especially with the jumper shorts), so if you think one or more of these should have fixed the issue, I'd love to give it another try.=What I did before it broke=
I was unable to my Windows 7 installation due to Windows Update being corrupt (unrelated issue from a couple years ago, no fix). So I moved all of my essential files from my misc partition, D to my Win7 partition, C.
I formatted my D drive, installed a fresh Windows 7 on it, and began upgrading it to Windows 10. The upgrade got stuck for a few hours at 99%, and I found on the Internet that stopping wuauserv and restarting the upgrade was the way to fix it.
I did that, but this time the upgrade just failed.
I started the upgrade again, and a few percent in, I decided to just reboot my computer and start the Win10 upgrade from there.
Instead of taking me to the boot menu to let me choose between my 2 windows 7 installations, it immediately took me to a "upgrading to Win10" screen.
After the upgrade was done, I completed the windows 10 configuration wizard.
At the end of the configuration wizard, I got a weird error window related to "GetCurrentOOBE.dll" and this made me think that the earlier 99% installation was the cause and my Win10 was broken.
I restarted into Win10, and realized my config wizard settings weren't saved.
Both the dll error and the config wizard settings not being saved, made me suspicious enough about this new installation that I just wanted to start it all over again.
I went back to my original Win7 partition to restart the process, but I decided to watch some YouTube to unwind. After an hour or so, my external monitor started flickering and the color got weird (I recorded a video of this if necessary).
I fiddled around with the VGA cable for a bit, and both screens froze (I sadly don't remember if the flickering stopped) and I had to hard restart the computer.
I deleted the windows 10 partition via diskmgmt.msc, and started installing win7 to the same place (at some point during this step, my mouse cursor got a bit stretched and there was yellow dots on it).
During one of the restarts that happen when installing windows (most likely the first one), my computer slipped into the black screen/boot loop issue.