My phone fell inside water

@bosho4164 must be the season for mobile phones to get water damaged. We see a lot of this lately.

For now, you must stop continuing to try to charge, sync or otherwise use your phone. This potentially can make a bad situation worse. This may further damage your phone.

The very first step I would take is to disassemble your phone. Since iFixit has a few guides for this phone Xiaomi Redmi Note 8 use those for as much as you can. For the rest of it, like the main board and charge board removal, use something like this video. Remove the main board and the charging board. You will have to remove all the EMI shields from those two boards. If you do not remove the shields, you are not cleaning the board.

Now take a careful look at all components and connectors. Thoroughly assess the damage. Look for any corrosion, even evaluate the pins in the connectors etc,. Take a look at all connectors as well as cable ends. Once you got any 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 all the steps are 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. You do not need to leave it to dry after cleaning. Isopropyl alcohol in the higher concentration will evaporate quickly and dissipate the water.

The importance here is the cleaning. It would of course be best to get it ultrasonically 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, I always consider replacing the charging board. There are not a lot of schematics for this and replacing it, is usually better. Those boards are luckily not expensive and still readily available. Replace the battery and reassemble your phone and re-evaluate. For as long as you have not cleaned your board and replaced the battery, everything will only be a guess. Keep in mind that water damage is the hardest to troubleshoot and to repair.

Anything that may appear odd to you or looks damaged, you can always take some pictures of that and add those to you Question. That way we can see what you see. 在已经存在的问题里加入图片

While you work on your phone, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has a device with the same issues as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.

Repair is War on Entropy!