.... Does anyone have any suggestions for the next option? ....
Try another electrical socket. This would be my main suspect.
Rule out bad power switch by disconnecting switch cable from MB header and briefly shorting the two pins.
Confirm PSU turns on by shorting green wire with any of the black wires on the 24-pin harness while one or more fans are plugged into the 4-pin molex connectors.
Replace/reseat PSU power cord depending upon results. Check PSU switch if any is on? Reseat power mains on MB, CPU and GPU. And modular connections on GPU.
Do any LEDs glow on PSU, MB, case front or back panel I/O?
It would be highly unusual for there to be power and the PSU functioning if the PSU, CPU and system fans didn't at least try to start up briefly. Though a system short will cause a properly designed PSU to detect the short and immediately shut down the system to protect it. But usually you see a brief movement of the fans.