Which parts need replacing after possible water damage?

@fixmyiphon81689 besides replacing parts you also have to make sure that you treat the potential water damage. Otherwise even your new parts may not work since corrosion on the mainboard will be ongoing.

The very first step I would take is to disassemble your phone. Use these guides iPhone SE 2020 to help you disassemble your phone. Take a close look at all components and connectors. Look for major corrosion, evaluate the pins in the connectors etc,. Take a look at all connectors as well as cable ends. You will have to remove all the EMI shields. If you do not remove the shields, you are not cleaning the board. Once you got the gross contamination cleaned, use 90%+ isopropyl alcohol and clean your parts some more. For a proper cleaning, use this guide. It was written for an Apple iPhone 3G but it is still pertinent to your phone as well. I can not stress the importance of a good cleaning enough, so do it over and over while replacing the alcohol after each cleaning. It would of course be best to get it professionally cleaned Do not forget to replace the battery. This is a must and not an option. It will fail if you do not take care of it now. After that, reassemble your phone and re-evaluate. For as long as you have not cleaned your board and replaced the battery, everything is just a guess. Keep in mind that water damage is the hardest to troubleshoot and to repair. It does not matter if is was exposed for 2 seconds or 2 hours, what matters is where the water (particulates) did the damage.