Dead iPhone Battery

I left my iPhone 7 in storage and unused for about a week or two dead (0% battery) and when I went to go charge it to use it again, it is just has a black screen and does not show the red low battery symbol. I’ve left it sitting for 5 hours plugged in and it still will not turn on or show anything on the screen. Do I just need to get the battery replaced? I have an iPhone 11, but I wanted to turn my iPhone 7 back on so I could back up the photos I have on there.