Problems with M3800 - Screen goes black

I have had a M3800 for a year and a half. I really like the size and portability.
However, the screen flickers and goes black randomly. Sometimes once a month, sometimes 5 times a day. When it was still under warranty, I had the screen replaced with a new one because the touch was not working and hoped that would solve this problem. However, the new screen did the same thing: randomly it would flicker then go black. I would have to force a shutdown (hold down power) then reboot. If I rebooted immediately, I would get 8 beeps (no video hardware/LCD). If I removed the bottom cover and un-plug the LCD screen and let it sit for a bit (cool off?), when I plugged the LCD back up and turned it on it will work again.

Since I had a new screen, I thought the problem was the motherboard. I ordered a new motherboard and just installed it. While in the bios setting everything up, the screen went black again.

I have also tried to boot using just the HDMI output (even unplugging the LCD), but it gives 8 beeps. If I can get it to boot, I can plug in the HDMI and it will work.

When it does finally boot, I can run diagnostics and it says there is nothing wrong.

Knowing the new motherboard is not the issue, should I order (yet another) new screen?

I am very frustrated, I need a working computer.

I am considering ordering an XPS15, which is basically the same as the M3800 just a different video card. Maybe I can get one cheap and use my existing memory and SSD. I don't think I need quadro, I mainly use AE and 3dsMAX

 

Is it outside of warranty? You sound more proficient than I am regarding comptuer repairs. But if I had such a new laptop (1.5 yrs is still new to me) but no longer had a warranty, I would probably reach out to an authorized local Dell repair technician. Are you in the USA? I would ask the rep how much $ to diagnose and then to give me an estimate on the repairs. Depending on what the diagnosis and estimate is I would consider letting them repair it... else I would get a newer machine and with a longer warranty. I probably would not buy a new display without first knowing that would actually fix it.

Here is where I'd go to get the ball rolling. They could put you in touch with an authorized Dell tech.
http://www.dell.com/learn/us/en/19/services/out-of-warranty?~ck=mn