As far as a source for parts, if IFIXIT doesn't have them then a simple Google search should get you some info. Just make sure the source offers guarantees on their products. If you disassemble your device, be sure to look for signs of corrosion around any connections/chips/ etc. If you find any, I would recommend cleaning the logic board (or having a repair business do it) in an ultrasonic cleaner with electrical component cleaner ( like Branson EC) . This will ensure that there isn't corrosion or oxidation anywhere that will cause further problems after you install a new battery. Good luck!