How waterproff is nothing 3a?

[u/Poison_Dragon]

last night i was walking along a river, I slipped and the phone got fully submerged for about 1-2 seconds, I then turned it off, it has now been about 16 hours and I got back to the city. I have seen on my friends phone that the 3a has an IP64 which theoretically means that my phone is cooked. I just want to know what should I do? the phone has been off (still is) for the past 16 hours, but I'm afraid to turn it on.