If you cant login via console, you cant do a thing to diagnose.
Except maybe drop the SD card into another Linux host to check logs and the systemd journals.
Because its a Pi, the only recommendation I can give is to try out a better rated AC adapter.
Or exchange the USB power cable for a better one (thicker and shorter is usually better).
Pi's are very susceptible to poor power.
https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#power-supply-warnings
EDIT:
Oh KVM stands for "keyboard video mouse" for if you might have misunderstood!
Dont need a mouse but think thats obvious 