PKv, first I want to apologize for my suggestions. I am sure you tried them all.
First, unplug the radio for 2-minutes then replug in and try again.
Second, check the power output on your power supply. Once my Kenwood would not turn on and I looked at everything . Frustrated, I turned on my VHF radio and it would not fire up either.
My problem, well my radio problem
was the power supply.
Last, see if there is a IC-7300 chat room,
like this one to see if their is a suggestion or fix.
Good luck Brother.
PS: Is your transceiver hooked up to a computer program to run it via your computer? If it is, try to toggle it off and on using the computer program.