Hello!
It seems you've already tried the majority of the troubleshooting options, which is good!
This can also happen as a result of a failed bios update, however given that you tried to reflash the bios and it didn't pick it up, that should be already ruled out.
So as of right now, you've ruled out your SSD, RAM, and GPU, so that leaves your peripherals, PSU, and your CPU.
A few more things to try,
Unplug all your peripherals with the exception of your monitor, try booting.
Re-seat your processor.
Boot into safe mode and run the repair utility.
This along with @jayeff 's advice for checking the PSU and ensure you're computer is posting, should cover all our bases
Coco,