iPhone 5s looping apple logo and black screen

Hello,

I had an old Iphone 5s laying around which I had no clue what the problem was and since I need a backup phone right now I was trying to diagnose it.

When connected to the PC, it’s not recognized on iTunes and instead just loops between apple logo and black screen, with 2-3 seconds only of each loop. When connected to the wall outlet, it displays the restore iTunes symbol.

This phone is all original parts and i’m not sure where to begin, I’m probably gonna replace the battery first since it’s the easiest/fastest and go from there.

Tried all the reset/recovery mode button combos. On wall outlet, doesn’t turn on and eventually goes back to the iTunes restore screen. On PC, as soon as I connect it via USB it instantly starts the loop and no button combo can override it.

Any other suggestions?

Thanks

Miguel