Question Troubleshoot pc build - no power

[RioTubes]

Hi,
I can't seem to get power (i.e. fan spin for cpu cooler, gpu or psu itself)

System: Ryzen 3600 with stock cooling fan; Asus Rog Strix B550-F mobo; Sapphire Pulse 5600xt; Corsair RM550X; Corsair Vengeance 2x8 3200 DDR4 CL16 RAM; 1TB Samsung 970 Evo M2.2280 NVME storage
Outside of the case, I

1. Installed the cpu on mobo and locked it in place,
2. installed the cpu cooler, and plugged fan 4-pin into fan header
3. Installed each of the two Corsair Vengeance 3200 DDR4 CL16 RAM sticks into 2 and 4 positions
4. Installed and seated the M2 storage
5. Installed the Sapphire Pulse 5600XT into the PCIE slot next to the cpu;
6. Plugged 24-pin from psu to the mobo 24-pin slot
7. Plugged the 8-pin from psu to the 8-pin mobo slot for cpu 8.

Plugged the 8-pin from psu to the GPU
9. Plugged the HDMI from monitor to GPU HDMI slot

I then turned on the psu. Immediately, the light for the mobo's i/o circuitry lit up but no fan spin from cpu, gup or psu itself. No noise as if the pc was booting.
I reinstalled the 2 RAM sticks and graphics card again. Checked all psu connectors. Same effect.
I have another psu and hooked the 24-pin, 8-pin (CPU) and 8-Pin (GPU) to the appropriate sockets. Same effect. The light of the mobo's i/o circuitry lit up but no fan spin from cpu, gpu or psu.
Please help troubleshoot! I think the mobo must be DOA? Thank you