The only thing you suggested in 15 was getting a new radio. I still want to know why you think that would work if the radio that still works on the Uno doesn't work on the Mega.
Swapping radios to pin down exactly what broke is just common sense. I was a computer technician for 10 years and a mechanic for 5; swapping out parts and eliminating all unrelated items are standard troubleshooting procedure. Both units worked, then damage occurred. Swapping a potentially bad part with a known good one is just basic. If you ever troubleshot anything physical you'd know that. What I did was basic diagnostic troubleshooting.
I'll say it again - Both the wiring and the code on both radios worked prior to the damage.
So what I'm going to do now is get an Ethernet shield and a wind direction and speed sensors for the Mega and run a cable, and get another Uno, a 3 pack of radios, a pack of voltage regulators, a pair of soil moisture sensors, a solenoid water valve and relay. I'll use the radios for the valve and moisture sensors since those should have integer values not floating point ones that cause me problems trying to work into radio transmissions and use the Mega with the Ethernet shield since that one will have a lot of variables to work with and I can have them write to a file on the micro sd card from the Ethernet shield and get it via the network.