iphone x water damage

i was shooting video in sea water underwater video. i dont feel any damage at time. after battery low not getting charged. i tried to clean port but no hope. i given third party shop for to repair because i was out of my country for holidays. after he repaired phone boots and charging fine. but gps blue dot not moving while driving and now itunes not recognising my phone :(

how can i solve this. how much will cost if i give to apple care. am staying in UAE