Windows 10 Screwed up my Studio XPS 7100 - HELP!

I have a Studio XPS 7100 - out of warranty - and I recently upgraded to Windows 10 from Windows 7.

The upgrade seemed to work for a couple of week, but then the machine would go into Repair Screen mode, saying something went wrong.  I have tried to revert back to Windows 7, but the option is not there any longer. I have tried to go and use the RESTORE option, the FIX option, I have used downloaded the ISO or MEDIA TOOL.... Nothing is working. I ran Dell diagnostics and there are no disc errors or hardware issues. This is COMPLETELY a software issue.

Dell says my machine is not being tested for Windows 10 upgrade.

When I turn on my computer, I get the Dell start up screen, then I get a black screen with a small blue Windows logo and a message saying "Preparing Automatic Repair" It is there couple of seconds, then my machine reboots to the same screen, over and over and over in an infinite loop, saying "Preparing Automatic Repair."  

When I shut down the machine and wait a few minutes, it reboots and does the same thing.  I waited once until the next day and did get to the screen where it says I can reset the computer. When I do that, it starts "resetting" and there is a % counter at the bottom of the screen going up towards 100% - but during the process, I get a message saying there was an error and the machine was not reset.

Microsoft help forum has not given me any solution I have not already tried. I NEVER had a problem with this machine until this Windows 10 update.

So.....I have all my files off the hard drive (via Safe Mode) Now how do I completely wipe the drive from windows and reset it to factory settings?  I want to uninstall Windows 10 and put Windows 7 default back on this computer. please tell me how! 

THANKS!!!