Yes it will ruin. Water conducts electricity. The battery will short out if submerged.
The phone is probaly already shorted out and nonfunctional, changing the battery would likely do nothing as the damage is already done.
My question is why would anyone do this? But since you asked. It will ruin the battery.
My husband works for a major phone retailer - definitely don't immerse your mobile phone in water - with or without the battery as the phone's other components are not waterproof and it will usually void your warranty!
If you get the phone wet, put it in a bag of rice. The rice will help draw the water away from the battery.
take the battery out and put both the phone and battery in a container of rice, it helps dry everything out
Ruin the battery.
Yes, if the negetive battery cable is not connected propperly to the battery, it will ruin the alternator and probably kill your car.
yes it does
Most cell phones would not hold up to a drop in water. But you can try fixing the problem yourself. You'll want to take the battery out and let dry. But if a phone has water damage there should be an indicator sticker to tell if it's too far gone to fix.
Most definitely you can ruin it. Always charge an auto battery with an automatic charger that shuts down when the battery if fully charged.
No overheating won't effect battery but while it's hot it will still be hard to start since elec resistance increases with temp