iPhone 6 infinite boot loop after drop, please help!

What error number are you getting from iTunes? This could be an important clue.

As RBA8 suggests, this is most likely a logic board issue however lumping all logic board repairs as “pricey” is a bit of an oversimplification. At this point, it will most likely not be a DIY type of repair so you’ll have to consider if you want to pay someone to fix your iPhone 6 or if you are going to apply that money towards a replacement phone.

I would look around in your area to see if anyone offers micro-soldering repairs and ask them to give you an estimate. Then decide if you need or want to get the phone repaired (i.e. you may need the data if you don’t have a backup). Most shops offer a no fix no fee model so if the repair is unsuccessful, it won’t cost you anything but your time.