I worked for a company that sold electronic system into commercial airliners. The system we sold was the second back-up, ie they had 3 systems. Dont know for sure but I would imagine radios are similar given criticality.
Also was in an aborted takeoff. Turns out an oil pressure guage was bad. Tech comes aboard and fixes it. No deboarding. Took off 3 hours later. Something doesn't add up.