I am having a similar issue but for a new rig set up.  I am not getting any indication that power is flowing through to the MB.  This obviously prevents me from posting to BIOS and eventually installing an OS.  Is my brand new MB toast or am I missing something silly?  Every single component is brand new and I have not even started to add PCIe risers, GPU's, etc.

Base Rig Build:

MB: ASRock H110 BTC+, 13 GPU MB
RAM: Corsair LPX 8GB DDR4 DRAM 2133MHz C13 (2x4GB)
CPU: Intel Core i5-7400 3.0 GHz LGA-1151 6MB Cache + Standard Fan/Heatsink (yes fan is plugged into MB CPU Fan)
PS: Silverstone ST1500-Ti - 1500W 80 Plus Titanium
Power Switch: 2 Pin PC Power Switch Cable Momentary on/off Push Button Cable
HD: 128GB Sandisk SSD

Troubleshooting so far:

Tested PS on separate MB - OK
Reseated CPU and RAM
Removed 2nd DIMM of RAM
24 Pin MB Power and 8 Pin CPU power connected
Tested with SATA and 2x Molex power cables connected and disconnected
CMOS Reset + Remove CMOS Battery + Swapped CMOS Battery

Help me!