We have 4 Rad bikes, 2 minis purchased 4 years ago and 2 R runner plus models.  The two minis are primarily used when we travel and both have the S1304 codes. My wife's RR + is just over 2 years old and that bikes battery also has the code. The RR+ that I ride was new in Jan 2021 and has over 20K miles, the battery has been charged hundreds of times (after every daily ride) The newer RR+ has 6-7000 miles and that battery has been charged daily. We have seen no battery degradation on any of the 4 bikes. At this time I have no concerns with any of the 4 batteries. It will be interesting to hear what other owners are saying about their experience.

Maybe a Back up Battery would be cheaper and easier? 

That was great!  I can add this,  I am starting my third year of riding my RR+ and starting my second 10,000 miles.  Ride it daily 20-25 miles and charge the battery every day (with no loss of range thus far).  Ride RAD and ride for fun!

Maybe you should stop by a bike shop and ask for recommendations or help.  I do not believe that changing your shifter is difficult but you need to be certain that you have one that works for you and your bike.  I did take a look at options on amazon and found this:   
https://amzn.to/41adttq

As you can see this is not an expensive upgrade but I would make sure you picked the best one for your riding style,

You sure have lot of issues Muskie 1.  we have 4 Rad Bikes,  Mini ST, Mini4 and 2 RR+. Total for the 4 bikes we have ridden over 15,000 miles.  The folding bikes are for travel (the ST was ridden daily for 18 months until my wife wanted a RR+ She has logged over 1000 miles since getting it mid August,  My RR+ is approaching 9000 miles, I had a noisy motor issue and replaced the rear wheel/motor from Rad and have since repaired the original motor for back up.  My. point is before every ride I check the bikes over for any issues before we ride and upgrade or repair as needed (usually 20-25 miles per day)  the batteries get charged after every ride (that means daily unless it rains) and have never given us any problems.   I would like a lighter bike, but as almost 79 yo getting up some of the hills has become almost impossible.   My son has a Specialized Mid drive he likes, maybe you should try one of those.   But I will add that my son purchased a like new used RR+ in July and the Specialized has not seen much use since.  This is a Chevy - Ford issue, buy one you like and ride it and keep it in good running condition.

I purchased a pair of brackets that allowed us to use the walkie talkies that we already had,  Brackets were on Amazon and sold for both hikes and motorcycles,

Is your fender properly attached to the frame?  we had a squeaking issue with my wife's new Runner + and discovered I attached the fender bracket on the front not the backside of the frame.  I switched it to the rear and the squeaking stopped. 

I think you are over reacting, If you know how to take care of a bike,  the Rad Bikes are pretty easy. If you do have a warranty issue they may be a little slow, but they will get it resolved.  They had battery issues with their new Rover but have taken care of those,   other than the battery anyone can adjust brakes, seats, shifting mechanics etc. 

the motor on my RR+ got really noisy this past winter and I purchased a new rear wheel/motor/tire from Rad - cost at that time was $300 and it came ready to install and ride.  You may have problems purchasing a replacement wheel/motor from a different vendor if it is not compatible with the Rad controller.  You will need to call them to order the replacement, it is not listed in their accessory link

I think I would charge it, and check all of the connections on the bike after doing that.  Email Rad, but it could take a while for a response.

We have 2 Mini's and a RR+,  now my wife is considering a RR+ for her daily rides after riding mine for a week (I ordered new from Amazon tires for it).  We total 7000 miles a year on our bikes and have very few problems that I can not handle myself.  These bikes are a lot different than the old peddle bikes we rode back in the 1950's and need some attention to keep them running good. The folding Mini's are awesome for our RV travel adventures.  It is interesting that the range on the RR+ is significantly better than the other two bikes. I do think Rad could do us all a favor if they shared part numbers that they install so we could look for scarce parts replacement parts from other vendors when Rad is out of what we need.  The best upgrade I have made is the hydraulic calipers that I purchased from Area 13. 

Reply to them that no, your case is not closed and that you need some assistance - I have had the the same response but kept after them until I got the help I needed.  They like to sell bikes but are getting lazy when it comes to helping owners, especially new owners. 

This one should work - https://amzn.to/3Peb0Km
This device plugs into the controller on your bike.

However you are still going to need a crank puller,   there is a good article on the RAD site on how to do it,  also the puller is available on amazon.  You could check with a bike shop to see if they would pull the crank for you. This would probably be inexpensive and cheaper than purchasing the tools you may need.   Repair is easy but only if you have the tools. Rad should have the replacement disc but getting in contact with them can be very frustrating.

Magnetic disc $10 on amazon of maybe glue this one back together.

Watched it! looks like you are having  a great time with your RR.  I have the RR+ and have done of the same mods and also the front rack (orange) -  I am 78 and ride local Texas rural roads every day with my wife. I use my GoPro too but every ride looks the same as we ride the same 14.5 mile route daily.

Keep it up!