My screen went black after used in water

so i took my phone under water to click a few pics after taking few pics the screen started glitching and showing few lines so i took it out then when i plugged it in charger the phone started making noises so i unplugged it then i kept it in rice for 20 hrs the next the screen turned on but there were visible lines appeared then it worked for 20 mins and screen went dead but the phone was vibrating if pressed the volume and power button i took it to the service center where they said the board has gone and the water has emerged through speaker on the bottom

PS: i took it to the service center a month before because i was not able to hear in incoming call so they put a hole in the top where the speaker is for hearing and when i told them they said that the water did not go through the top it went from below but i after submerging in water i could see water in front and back camera

If anyone can fix it cheaply let me know