Can the fob be programed by myself or is a dealer/ locksmith job? First message I got was "fob not detected" and then "key damaged" after I changed the battery.

A locksmith might have the software. Here's a thing a dealer parts guy told me when I was asking about adding the remote start option to a 2011 Chrysler: the car will refuse to learn a new key fob unless it's plugged in to the home office through the dealer only software. General idea is about too many car thieves having too many ways to clone you existing fob so they patched that feature out of the on board. I kinda like it from the vehicle security angle, not so much from the pay stealership prices angle. Never researched it, for all I know it was a sales pitch.

I think I would try reinstalling the battery making sure it is in correctly +& -.

There was an issue with the key fobs where there is a fragile capacitor or diode or something that can be easily damaged when replacing the battery, that I thought had been resolved within a year or two of my 2009 Challenger. I damaged one of my fobs changing the battery and get the same error message when trying to use the pushbutton start. I removed the keyless start button from my dash and used that key like a normal key for a while, but later carefully changed the battery in my second fob, and that one works fine with the pushbutton start.
I'm the only one who drives my '09, therefore I don't worry about only having one key fob that works 100% correctly. The dealers charge big bucks for a new fob and programming, but I've heard you can buy a fob off ebay or Amazon, and that some locksmiths have the ability to program it at a much lower price than the dealerships.

Look into Alfa ODB, (use with laptop or tablet). I believe you can program keys with it depending on year. The software is roughly 50$ plus I think you need a wireless odb LM327 adapter. The WiFi version may work better if your phone is Bluetooth connected to your car.

Remember pursue at your own risk but here is a thread detailing adding/programming fobs in a RAM

The cutting edge is quite often the bleeding edge.

Program fobs Ram truck