phone not holding charge very long

Try going through these steps: https://deciphertools.com/blog/2014_06_2... Also check for apps that have crashed. Close your apps when you finish with them by double clicking the home button and either swiping up or pressing the X on them depending on which version of ios you have. The other problem could be an update downloading, or a short on the motherboard. You probably shouldn't go poking around on the board though. At least not until you have tried the above, and decided that you would rather have a broken phone than one that drains quickly. The replacement battery could be garbage too if you got it from eBay for $5 or something.