Dell XPS 8700 does not post after BIOS upgrade

My son was planning to upgrade the GTX745 in his Dell XPS8700 to a new card. After checking online, we found that before installing the card we needed to upgrade the BIOS in the system from the current BIOS (A08) to a new BIOS (A11 for Win 10 systems). We ran the BIOS on the system from within Windows (removed all external connections except Keyboard and Mouse). The BIOS processed through the first few steps and then during the verify process the entire computer shuts down. Now, the computer will not POST at all. I will turn on and stay on for approximately 20 seconds before shutting down before starting the entire process over again. This computer has had zero issues for 2 years and now after installing Dell's BIOS upgrade the entire system is apparently fragged. 

I pull the RAM out of the system and I do get an alert so at least there is some function going on. I have pulled the Nvidia card out of the system and am trying to get a signal off the onboard HDMI port. When I turn on the system I do get an acknowledgment that the monitor knows there is a source there. The monitor wakes from sleep briefly before going back into standby when it does not receive an actual signal in a timely manner 

I know the chances of there being any fixes are slim but I thought I would check with the community and see if anyone has suggestions. I called Dell for kicks and after dealing with someone halfway around the world who obviously had no clue on how to help me, Dell told me the system was out of warranty but they would happily sell me a motherboard. 

Thanks in advance to any help anyone is able to provide.

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