Hi @mrmchoul ,
According to the this (click on Compatibility > CPU) the BIOS is 7C37v1F. It is the same for all the Ryzen CPUs shown in the list, including your CPU. There are only 2 CPUs mentioned in any of the BIOS updates, yours is NOT one of them - see BIOS 7C37v15 2019-10-30
What are the ezy debug LEDs on the motherboard showing, when trying to start the PC? (see p.39 of the user manual).
If the CPU LED is on, disconnect the power from the PC and check that the CPU has been installed correctly i.e. no bent pins.
If no LEDs on at all, check that the PSU turns on (PSU fan starts?) when the power button is pressed. If nothing happens check the power button cable connection on motherboard (see p.33)
If it is OK check the PSU is OK by performing the paperclip test on it. Check that all the voltages from the PSU are all OK and if so and there are no debug LEDs there is a motherboard problem. Check the PSU cable connections to the motherboard.
Is this a new build or a CPU upgrade to an existing build?