Hi Kev!
I did some searching for it and came across a post you’d made a few months back on a post similar to this one. (Roger Select Battery Replacement - #27 by kevels55)
£130 is a horrific amount of money to pay to me for something that could be down to a battery replacement haha, I saw that you mentioned a 503030 battery. It seems to be the same size, look and have at least 2 of the wires the current one does which is hopeful, I think the only issue I’m going to have is figuring out how to solder it haha. That’s if it is a battery issue in the first place, if not I’ll have to fork up the £130. 
I might have to see if I can find someone that knows anything about soldering to help me with it, surely there’ll be someone in a repair shop with some idea. 
Thanks !