I've got an ASRock B450 Steel Legend that I'm trying to diagnose for no reaction to the power button.
The SIO receives the PWRBTN# signal and sends PSOUT#, but the CPU doesn't return SLP_S3# so nothing further happens. I have been looking around the board trying to figure out why and I happened to touch the STEP-DOWN CONVERTER NB685GQ-Z (UP10 in photo) which was VERY hot (like burn your finger). This seems to provide VDDP_S5, and indirectly, VDDCR_SOC_S5, which the CPU needs in order to handle the startup signals.
The VCC voltage powering the converter does not look right....
