Why is it turning on by itself?

So I accidentally dropped my ipod nano 4th gen in clean water but it only stayed there for about just 2 seconds because I quickly grabbed it back, it went for just about 1 feet under. I turned it off before putting it in a bag of rice. After 3 hours, I hastily grabbed my ipod back and I turned it on, it works fine, the screen is perfect, it can play songs, I could still connect it to computer...

But the problem is everytime I turn it off, it turns on by itself after 1-3mins. I also tried locking it after turning it off but it'll still turn on by itself, I basically have tried everything to fix it... It's never happened before I dropped it in water... I'm wondering if water really destroys ipod even if it went in the water for just 2 seconds???

-->Is my ipod damaged already?

-->Should I wait for about a week to a month to see if it will return back to normal?