With a leased phone?

My iPhone got wet and doesn't turn on. Its leased so to do the upgrade i have to give back the phone, and since it doesn't turn on at all they will charge me like I'm buying the phone when i give it back. I don't have any protection on it. If i say to buy the phone it will cost me $320, but i don't know if by just giving it back they will charge me less. Something else, a new phone is being added to my line. Could i ask for a exact same phone as mine and put protection on it and say that it got lost so i get a new phone and at the time i have to give back my phone i give them the one that was just added to the plan. And my family member gets the phone that is covered by the protection plan, or it wouldn't work?

You can ONLY turn in the original phone issued for that line in FULL working order. Period. So your options are clear, get that phone repaired by Apple *Paid out of YOUR pocket. If you can't turn in a working phone, you will need to continue paying on the lease to the end or get it repaired by Apple (not a third party, Apple).

The phone issued on YOUR line has an ESN (CDMA phone) or IMEI (GSM phone), that is activated on your line, so NO other phone will work as a sly turn in. To replace the phone it will cost you the full retail price of the replacement phone, unless there's a lost/broken phone clause in your contract.

Yes