I can only say what I would personally do in your position if the battery pack is failing.
There are a number of pannier mounted battery packs on the market that provide 36v at really useful capacities. The controller from the swytch battery pack is useable, but will need mounting in the pannier somewhere (a lot of these pannier battery kits have a compartment for that). The black and red wire from the controller with the XT60 connector on it will be connected to your new battery. You’ll need an extension cable to connect the wheel to your new controller position, and ditto for your PAS. Your display from the swytch bag is useable, but the cable needs extending to the handlebars, and you’ll need some sort of handlebar clip to attach it rigidly to the handlebars. IIRC there are now two or three wires left over from the controller that probably perform some switch function, that you’ll need to understand so you can resolve them.