Dell XPS 17 L702x: blank screen, no splash, no bios, no beeps, no boot
I have a Dell XPS 17 L702x that I was prepping to sell. The basic specs are:
16GB of RAM (4GB x4)
NVIDIA GeForce GT 555M with 1080p 3D screen
500GB 7200 RPM HDD x2
Windows 10 Pro
Like I said, I was prepping to sell the laptop. The laptop was functioning properly. I had wiped the HDDs clean and was in the middle of performing a clean install of Windows 10 pro from a USB drive. I have done this before and never had a problem. The install started correctly. I selected the drive that I wanted, and the installer wrote the files to the drive. The laptop then restarted. The power came back on, the fan started up, and I could hear the optical drive and HDDs spin up. However, the screen stayed blank/black, and the Dell splash screen never appeared. The activity light on the USB drive never comes on. The normal functions keys do nothing.
Here are some troubleshooting things that I have tried:
I removed the RAM and HDDs. I get the typical 2 beeps from not having any RAM. Motherboard seem ok.
I have tested the RAM in my work Latitude E6430. The E6430 will boot with the RAM from the L702x. The RAM seems ok.
I have tested each stick of RAM one at a time in various slots in the L702x. Same problem, blank screen, and no beeps.
I have connected the HDDs to the E6430 with a SATA to USB cable. I can format and read/write from/to the HDDs. The HDDs seem ok.
I removed the top cover and removed the button battery to reset the BIOS. I held the power button down for an extended period of time. Reassembled everything. When I first power the laptop back on I get 5 beeps for removing the battery. I get the same blank screen when I power it back up a second time.
I used Rufus to create a bootable DOS USB. Holding down END and plugging in the power cable will cause the laptop to start up, but I'm still left with a blank screen.
At this point I have run out of ideas. Please let me know if there is anything else that I can try.