I just finished a boxing match with this board myself.  I tried to use a processor from a previous build and that TB 250 board had shorted out in a puff of smoke.  I had thought the CPU was undamaged.  The CPU worked in this board for about 2 weeks.  After that, the symptoms were just as you described.
I ordered a new CPU G4400 and when I installed it;  at first, same problem.  After hitting myself on the head, I noticed the CPU fan plug was not fully inserted and the CPU fan was not even spinning.  So double check the CPU and Fan with another one if possible.  Since you replaced the Mobo already, I would say your CPU may be next on the list to replace.
Also, don't use a DVI to HDMI adapter on the Mobo.  I found that I couldn't get into the bios with the adapter and had to find an old DVI to DVI cable that would work.
After setup, I am able to use a DVI adapter with HDMI dummy plug, but can't see anything until it hits windows loading screen.  This could be a simple setup in the bios fix, but just don't feel like hanging out in the 100 degree mining room messing around with it.  If it works...I don't mess with it!  Good Luck