I would suspect that some device is the issue and taking it to the minimum configuration (removing all cards, drives, memory but one, USB and all peripherals (including mouse, keyboard - or try different ones)) will isolate that device.  Otherwise, I'd say your BIOS is corrupt - which, unfortunately, is not common and there is not an common or consistent fix - and if that is the case, then there are limited things you can try:  1) clear NVRAM (which you said you tried with no luck), 2) reflash BIOS (but if you can't boot to any media, that's out ot the question too), and 3) replace the motherboard. Good luck.
I recently installed Windows Server 2008 R2 Enterprise and activated Hyper-V and installed all available updates.  Upon reboot i am unable to boot into the OS, Systems settings, and/or Bios settings.  Once it pauses for a few seconds with the message "Press Ctrl-E for remote access setup within 5 seconds" it just continues in this loop.   If I select F12 for to modify setting it says it is entering setup, however it never makes it into the settings.  If when i receive the above message and I press CTRL-E it will go into the remote access settings.   Thanks in advance for any help!!!!
Poweredge T110