Phone stuck in restart mode.

I've already read the article on "iPhone stuck when turning on" it was absolutely unhelpful and its suggestions implied that I could plug it into a laptop and find the device then went over how to restart it. My phone was very much full so I deleted tons of apps and messages cleared almost 15 GB and it still wouldn't open snapchat, photo, Spotify etc. I thought well if I just cleared that much there must be a problem and I restarted by phone. Problem was when it was booting back up it got stuck on the apple logo and hasn't moved for 30min. Something is definitely wrong, I tried maybe redoing it and now every 5-10 min it goes from stuck to turned off and then without me touching it tries to auto boot back up. So now its just shuffling back and forth but mostly just stays in the stuck mode. I really need help I have online school assignments due that depend on my logging into the platform which needs mobile verification.