This is my wife's laptop. She has been using it for a couple of years after purchasing it refurbished. It is a Latitude E6420. It was a good computer for her as she didn't need blazing speeds but she tends to be hard on supethin, superlight hardware. The E6420 is built like a tank and did good until now.

The issue first presented as the OS (windows 10) progressing as far as displaying the light blue Windows logo and then stopping there.

I run a diagnostic and the result of it was this:

Error Code: 2000-0415
Validation: 8557
Msg: Cables - Check the following cables: LCD Cable

When first purchased it, I happened to have an extra SSD drive I wasn't using, so I removed the Original Windows 7 SSD and stored it away for emergencies.

Then I installed my own SSD, installed Windows 10 on it and the computer has been working great since it was purchased, until this inability to boot showed up.

I first tried to repair windows but I had no luck. It said the partition was locked and I couldn't either repair it nor install windows anew.

Then I tried using the original SSD with Windows 7 pro. This too doesn't boot. In fact, it takes me to a flashing cursor.

I also run Linux (both Mint, Ubuntu and a couple of diagnostic versions) off a thumbdrive without any issues, but I was unable to perform any repairs.

I have found another post regarding the error : 2000-0415 at these links: 

https://www.dell.com/community/Latitude/Latitude-E6420-Error-Code-2000-0415/td-p/5931009

and

https://www.dell.com/community/Laptops-General-Read-Only/E6420-Bios-A07-Diagnostic-false-positive-Lcd-Cable/td-p/3848975

The posts were useful to understand what may be going on, but since they are from 2011, I wanted to see if there were newer fixes I could apply, from BIOS updates to whatever else may be wrong with it.

Right now, my backup plan is to use a 125GB thumb drive I have to run Linux on it so my wife can at least have a computer for email and web browsing, but that's not a long term solution. 

Should I call Dell support? I think I might have purchased an extended warranty for it, but I am yet to look into that.

Thank you for your help.