@kyla123 replace the battery with a new one. there should at least be enough power to access your phone to get to the files you need to retrieve. you want to check your charging cable as well as the charging port. Make sure that there are no bend pins or debris in the connector. If all that looks good, you may have to replace the port and check the board for failed charging components. For that you will at least have to have the schematic and a multimeter. I'd start with a new battery.
A new logic board may make your phone useful again, but you will not get your files back. Those are stored on memory IC's on your board.