Great brand with impressive performance.
If the unit is still under warranty, you should be able to get it serviced by KRELL.
My advice - be careful and use a hair dryer - COOL setting on the HDMI port. Buy a new HDMI cable or use a spare to test It again.
Upon 2nd failure after this, unplug all cables from the unit. Make sure it is powered off and unplugged from power before doing this. Wait for 10 minutes. Then test again.
This should not be happening on such a high-end piece of gear. If it still doesn’t work, then it is definitely a port issue. You cannot repair this yourself and will need to contact KRELL.