Even though the chipset on the R7 supports the i3 9100 that does not mean the BIOS does. I would pull the CPU and closely examine the CPU socket for any signs of bent pins. 
Hey guys,  I was trying to install i3-9100 CPU into my aurora r7.I made a mistake and did not check the supported cpu list, Some reason I was assuming it will work just fine.Anyways, after installing the CPU, When I push on the power button, the computer turns on and off immediately.After that, I installed the old working CPU. But the computer is still on and off immediately.I did not change anything else, just cpu.I removed the CMOS battery and did the CMOS jumper reset, but that did not help.When I push the power supply test button, I can see there is power.What else I can try?
Aurora R7, turn on an off immediately, cannot see the bios screen