How to fix iPhone5 after fell in salt water 3 months ago

This is almost certainly not feasible---but for iPhone 5 with what is likely severe corrosion, you'll end up doing some basic alcohol-based cleaning and be left with a phone that will have multiple components that need replacing because they are eaten by water. You could sit with a donor board and transfer components one by one, but the likelihood of a good outcome is probably slim.

Step one is a good cleaning and then post some pictures of your board and we can help advise you if it seems like it would be worth it to continue to work on it.

jessa

Paul, the major issue you will run into is corrosion damage. Salt Water will get your components to corrode very severely. The very first thing I would do is to disassemble it by following this guide. Take a careful and close look at all components and connectors. Truly assess the damage. Look for major corrosion, evaluate the pins in the connectors etc,. Take a look at all connectors as well as cable ends. After that I would suggest that you clean it a couple of times in sterile water, not drinking water (that might have helped right after it got submerged in the sale water). Use a soft brush and clean it very, very thouroughly with the sterile water. With the amount of corrosion that I envision, you will most certainly have to remove all the EMI shields. 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 a 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. Do not use compressed air for the cleaning since that can drive liquid as well as corrosion particles into areas that will cause trouble later on. Do not use drinking water, if you need to use water, use sterile water. Also, you do not need to leave it to dry for a day. Isopropyl alcohol in the higher concentration will evaporate quickly and dissipate the water. The importance here is the cleaning. 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. Also, I suggest to replace the lightning connector. The guide for that is here Yes, do replace the battery for sure. Use this guide for that. Keep in mind that water damage is the hardest to troubleshoot and to repair. It only has a slim chance of survival and may never work again. Hope this helps, good luck.

3 months with salt water inside. This thing has probably rotten all the way to the bones by now, don't expect any economical repair. Just throw it away.