Here are our recommendations:
- Test the system on a minimal configuration out of the chassis. Remove all memory looking for beep codes.
- If no beep codes check your warranty options to replace the board since you have covered most of the troubleshooting. If the system beeps, add just one memory module at the time and try to boot up.
I managed to solve it disconnecting the DVD drive as well at the hard drives, and having the BIOS on a USB stick. My system then booted and I was able to recover the bios and reset the settings.
All happy now