Water damaged phones are always at risk of developing other issues downstream. It’s certainly worth cleaning it inside to see if it solves your problem. If it does and it lasts, it was a worthwhile endeavour. If it doesn’t at least you tried and then you can always sell it for parts. Unfortunately, on the iPhone X, the logic board is a dual-layer sandwich design which makes a full DIY repair very difficult if not impossible.
Here is what you can try…
- Open your phone and remove the logic board
- Inspect the logic board, especially around the connectors and look for corrosion.
- Inspect both sides of the board.
- Put your board in a container with >90% isopropyl alcohol and let it sit for a while.
- Use a soft brush, like a toothbrush and lightly brush away any corrosion you see.
- Rinse in alcohol and repeat.
- Let it air dry for a day.
- Re-assemble and hope for the best.