***[link|https://www.ifixit.com/User/4267648/Becky+Dale|Becky Dale|new_window=true] ***sounds like you have come to the point of having to change the battery. This device is a bit of a bear to work on. You will have to remove the motherboard since the battery is located beneath it. Use this guide [guide|52142] to do so. I suggest that you take plenty of pictures a you work on it. It will help you for the reassembly and you can also post pictures with your QUESTION if you get stuck and need further help. Even so it's a chore to work on it, it is definitely the right thing to do. We are here if you need help to get it going again. Repair is War on Entropy.
[guide|21499]