troubleshooting new build A520M-ITX

Sorry to hear that, let me know how it goes with ASRock Tech Support.
Good luck

Thank you very much. I learned about the asterisk this morning looking at the QVL once more. If the QVL is to be believed the Ryzen 5 3600 should be supported with any BIOS revision. I replaced the GPU with a known working unit and behavior did not change. LEDs on the GPUs show power, but no output results. plugged a testing module into the PSU motherboard connector to verify motherboard power, then re-seated the motherboard connector just to be sure. I will next remove one stick and leave it on for 5+ minutes. Again, my thanks for your guidance.

I completed assembly comprising the A520M-ITX/AC motherboard, Ryzen 5 3600 CPU, 16 GB Corsair Vengeance LPX memory, Samsung 970 EVO NVME, Asus RTX 2070 GPU and Corsair RM 750 PSU. On first boot I don't see the BIOS screen. The GPU's power indicator light shows power, fans are operational, but no display.

I double checked the CPU power cable and it is well seated both in the PSU and motherboard. I removed and re-seated the GPU also. I was wary of a possible incompatibility between the Ryzen 5 3600 and the A520 chipset but the CPU QVL shows compatibility at all BIOS levels, albeit with a red asterisk beside the CPU name, and that red asterisk is not explained anywhere I could find.

I do not have an internal speaker so I cannot hear any beep codes. At this point I do not know how to diagnose further, and would greatly appreciate advice/guidance.