I used water damaged iPhone for an hour before it switched off

Alright, there are lots of lessons learned in this unfortunate turn of events.

Never, ever turn on a phone that has been in contact with water. If you have any doubt whatsoever that water got in, get it to a shop as soon as possible, preferably one that has the proper tools to decontaminate a water damaged phone (ultrasonic bath).

Second, don't bother with rice...not for a minute not for a day. All it does is give you a false sense of security thinking it's actually helping. It's not...not at all. The water is inside the phone, on the logic board and under the shields, even under the IC's. The rice is nowhere near where the water is. So while it “may’’ soak up some water vapour, the real problem is the mineral deposits that can cause short circuits or the corrosion that is taking place as the water evaporates. Leaving the power on the device accelerates the process. The longer you let a phone sit in rice, the more time you are giving corrosion to damage your logic board. The saltier or harder the water is, the more damage will occur. The water needs to be displaced, not evaporated. Here’s a great video that summarizes these issues.

On some phones, rice treatments appear to work. But those are phones that had minimal water ingress and not anywhere near a danger area on the logic board. They would have recovered regardless of the intervention.

If you want to try something yourself:

• Open your phone and remove the logic board (follow this guide)
• Inspect the logic board, especially around the connectors and look for corrosion.
• Inspect both sides of the board. Unfortunately, most of the board is covered in shields. That's usually where the damage is occurring.
• Put your board in a container with >90% isopropyl alcohol and let it sit for a while.
• Use a soft brush, like a toothbrush and lightly brush away any corrosion you see.
• Rinse in alcohol and repeat.
• Let it air dry for a day.
• Re-assemble and hope for the best.

You should also replace the battery if it has swollen. Resist the temptation to pop it to let the gas out. A compromised Li-ion battery is a fire hazard. If the device appears to power up but behaves erratically, then use a tool like 3uTools to flash the firmware as it may be corrupted.

A professional repair shop that does water damage repair may be able to recover your phone or the data because they have access to pro-level ultrasonic baths and specialized cleaners as well as the skills to troubleshoot your board. Many shops have a no fix/no fee policy so you don't have to spend money to find out if the phone is fixable or not.