when I try to on on it it won't

@vitalisononuju that sounds like a bad battery. It may take a charge but does not hold a charge. I would suggest to replace it and then re-evaluate your phone. Since iFixit does not have a specific guide for this, use something like this video replacement batteries are readily available at plenty of online stores.

While you work on your phone, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has a device with the same issues as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.