Pro4 will not post, no usb lights

I am afraid I bricked my motherboard, please tell me I am forgetting something stupid.

I went to install a new 1660 Ti. I had to reroute the usb 3.1 header (bad cable management when I first installed it) so I removed it and plugged it back in. Same story with the sata cable. The usb cable was real tough to remove, I had to wiggle it a bit, add some pressure to the mobo, but not too much that I thought I damaged anything. I got the gpu installed, and it powers up (leds turn in) both with an 8 pin connected and without.

However, I turn on the power, case and cpu fans spin, gpu lights and fans are on, but no display. I have a 2200G, so I moved the hdmi cable between the gpu and the motherboard hdmi port, nothing. I removed the gpu and went back to my old configuration, nothing. No asrock splash screen, no post, and no keyboard or mouse lights (both are plugged into the same usb ports on the back of the motherboard). Cables are all plugged back where they were before, so I feel good about that. What did I screw up, and is there a way to test to be sure?

I double checked, and the cables were not the problem. However, I completely forgot to clear the cmos. Once I did that I was able to post and boot into Windows.

I suspect the reason this happened was because I had set the UMA graphics controller setting in bios to "forces". My amateur assumption is that this creates a conflict once there is a discrete GPU installed. I haven't had a chance to try installing the GPU again, so we'll see what happens when I do.