Latitude e6440 With Boot/Stability Problems

Video of diagnostic tool running which ends in problem discussed below (actual boot starts around 0:50):

System Specs: Dell e6440 laptop i5 processor (4th gen with integrated graphics) 500gb hard drive 4gb RAM Windows 10 64 bit (upgraded from Windows 7 professional 64 bit) Connected to Dell Pro2x dock with dual monitors until trouble started

What I would like to do: fix a problem this pc has with powering on and remaining on and stable. Currently cuts off for unknown reasons.

The background: I found this computer in a thrift store without a hard drive and apparently having suffered a fall which damaged the outer shell. The internals still worked so I picked it up to work on as a project. I ordered an eBay lot of parts including a new top shell, motherboard... mounting shell? And a new motherboard and bottom cover.

Two weeks ago I disassembled the original unit and reassembled it with all the new parts and it seemed to go pretty well. I was able to install Ubuntu and mess around with that os. I am more of a Windows guy however and last weekend I downloaded an oem Dell Windows 7 image which (probably... I checked with Dell customer support for what was originally on the laptop) matched the license on the machine. I used poweriso to make a bootable usb, and installed it on the laptop. I downloaded the drivers from Dell and tried to install them in the correct order. Things more or less went alright. It was running Windows 7, then I updated to Windows 10 on Monday night, then installed Steam on Tuesday night and downloaded Civilization 5.

The Problems: the first major problem I noticed was that during the Civilization 5 download the speed of the download would drop to zero and then jump back to anywhere between around 100kbps an 3mbps. I turned off the monitors connected to the pro2x docking station and went to bed. A few hours later I checked on the download and it had finished. I went back to bed, but then when I checked it in the morning I couldn't seem to get it to wake up from sleep. I chose to leave it alone and come back that night after work (now it is Wednesday).

Returning that night I found it would no longer send any video signal through the docking station. I took it off the station and then found I couldn't get it to boot properly. The power would turn on but most of the time the screen seemed to not turn on. When it did it would start to boot but turn off only partway through the process. Pulling the battery and clearing the remaining charge by holding down the power button for thirty seconds or so provided the best result when it finally managed to boot into Windows, but it ran slowly and black command prompt style windows opened before any program or utility showed on the screen, then the power would once again cut off.

Booting into safe mode gives the same result. Booting into the bios utility gives the same result. I have swapped out the RAM and gotten the same result. I swapped out the hard drive and got the same result. I checked that the heat sink was properly contacting the CPU and am pretty sure that is alright as well.

This morning I turned it on and ran the bios Diagnostic utility until it cut off and recorded the results using my phone and plenty of seemingly heavy breathing. The good stuff starts at about 50 seconds in. As you can see, when the screen cuts off the fans keep going.

Things I have yet to try: swapping the original motherboard back in (I'd rather not as it has a bios password set up that isn't going anywhere)

Things I suspect might be the problem: Corrupted bios due to bad update install by me Bad CPU Bad motherboard Virus from Windows 7 install (would this effect even the diagnostic tool?) Overheating problem Improper timing of recent sacrificial offerings to Poseidon

Any assistance is greatly appreciated. I am a fairly technical person who can follow instructions well enough. Thanks for reading this extremely long post!