"Broken iPhone 13 with back damage and connectivity issues: I dropped my iPhone thirteen without a case from a very tall place, and it landed on the back and basically smashed. The back of the iPhone is lifting, and I am unable to connect to the internet or use wifi, as well as use cellular. Is it scrap or is there potential to save it?"
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Using an OtterBox and Liquid Fixes:
Take the as a learning experience, knowing to use a cover; OtterBox being a superb example. And, as long as it's not covered by AppleCare, then look into using liquid fixes. I've had my iPhone 13 Pro Max for literally years, and not a ding is on it when taken out of the case.
Note:
Placing liquid fixes to the iPhone's screen (i.e. Liquid Nano or Liquid Armor) would cancel your AppleCare coverage. So, avoid using it, if you have AppleCare on your iPhone.