Tablet charges but keeps rebooting

Hi all. My Samsung Galaxy Tab A 8.0 has been having a problem lately. When it's not charging, it won't turn on at all and it's a black screen no matter what. When I do charge it, the battery goes up, however, it keeps rebooting. The home screen never pops up and it never goes past the stage where it forms the logo “Samsung" . It just stays at the stage where it shows the battery percentage but nothing else happens. I've tried wiping cache partition but it didn't work. I'm scared to do a factory reset because I have some really important files and I can't really save them now. I'm pretty sure I need a battery replacement but I wanna know for sure what the problem is since it still charges but keeps rebooting and won't start up without charging. Thank you.