Build a PC Flashback LED is flashing when power Supply turned on


TS Rookie
Its my first build and I think my motherboard isnt working, but more specifically I want to know why the flashback led is flashing when I turn on the power supply. Power is going into the motherboard; the standby light comes on, as well as the Flashback LED, but when I attempt to turn the computer on with the power button on the case, nothing happens. I ensured both the ATX power connectors were fully in, everything is connected, RAM is in, but the computer will not boot. Also, I might have have connected the power to the case in at the opposite ends (ground to power and power to ground), but it has been reversed, and if that is the problem, would I have to replace the case or the motherboard?

Here are the specs
-ASUS M5A97 motherboard
-Fractal R4 ATX Tower Case
-AMD FX-8350 8 core AM3+ 4GHz
-Kingston 120GB 2.5in SSD
-Corsair TX650
-Kingston 8gb HyperX DDR3 Ram