Phone won't turn on, but vibrates every 7 seconds.

@valenciyaaaaa start by replacing your screen. Your phone vibrates because of a broken display. Once you have that fixed you can check and see if A. the vibrations stopped or B. if this is just a bootloop related to other issues. Again, screen first then re-evaluate.

Since iFixit does not yet have a guide for this, use the one from here Replacement screens are readily available and not to expensive.

While you work on your phone, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has the same problem as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.

Repair is War on Entropy!