Stuck in boot loop after possible water damage

Hi, While on holidays I dropped my phone on the beach and a wave hit it, it was covered in sand etc and it was wet. The phone, however, was still turned on and the screen still worked. I locked the phone, and removed the sand from the charging port and between the buttons. But when I turn it on, it goes to the "1+ Powered By Android" screen, and it doesn't go past that. I also can't reach the recovery screen, but I can get to fastboot mode

I left it in rice for a few days, to no luck and I put it in the hot press overnight which didn't work either.
I also tried flashing the stock rom from fastboot mode, and flash a recovery rom too, but it didn't help at all.

Does anyone have any suggestions on what I should do to try and fix it?
Cheers, Adam.