Swelling phone on the verge of exploding

I have an iPhone 7s that is on the verge of exploding.  It was covered by the assuron insurance so that I paid $150 to get a replacement. No problem right?  ATT is insisting that I MAIL the phone to them. It literally is locked in a metal box as it is on the verge of exploding. When you mail packages, you have to sign a representation that you are not sending any dangerous materials. I have gone round and round with ATT. I’m happy to bring it to a store, but I can’t mail what is tantamount to a bomb in the mail because ATT can’t seem to understand that it is ILLEGAL to knowingly mail dangerous packages. I seem to get nowhere on the phone or at the store.