Hi Biscitt,
I am afraid that I am no expert at diagnosing or mending these systems.
My own dealer has been very good, but was unable to help me with my own out of warranty battery problem. Fortunately my problem was broken connectors at the battery and the charger and this was relatively easy to carefully repair with the help of a friend who knew a fair bit about electrical systems and we really only replaced the broken Yamaha connectors on the battery and charger with cheap replacements bought of ebay. Luckily for me this worked and afterwards my battery could be charged and worked as before when attached to the bike.
What it highlighted to me was the complete lack of support by Raleigh for problems people have with Yamaha ebike systems when the warranty has expired. I think this is more about Raleigh and the customer service they provide for customers after their warranty has expired than the dealers who sell the bikes.
Your problem could be quite simple to fix but for most people faced with a dealer saying "fix it yourself " or "buy a completely new large expensive component like the battery or motor" as the choices given to you are the opposite of what good customer service should be.
In my opinion this is just not good enough with more and more of these bikes being sold. I do not think there is anything wrong with the Yamaha system and I really enjoy riding mine and think it is pretty robust but they should last longer than the two year warranty period and there should be somewhere they can be sent to have problems that arise after the warranty has expired assessed and repaired at a fair price.
Good luck.