Just to be sure:
- Does the radio work properly when using the buttons on the front?
- Did you put fresh batteries in the remote? The correct way??
If the answer to those is "yes", then I really don't have a clue what might be happening. Perhaps you can find someone (or a dealer) with a remote you can borrow to see if a different remote will work properly.
I searched Amazon and found you can buy a new remote (for what I think is a ridiculous amount of $'s):
https://www.amazon.com/IRV32V2-IRV32.../dp/B07VVGJ2RY
Maybe a local RV dealer can get you a new remote cheaper?
The other option is to get the iRV app on your phone and use that to control the radio. I have proven that it works fine with my phone, but I don't really listen to the radio much so I usually just use the remote. The primary problem with the app is that you can't turn the radio ON with it. You need to power up the radio some other way before the app will work properly.