Akash

There is few possible belong to that faults.The common problem with SWI issues.

First check that loud speaker option greyed out or not on call if not that is the problem related to Audio Ic.

That is the issues of audio ic that can be fixed by hardware.

Behind all iPhone the iPhone X series have so much easy solution for error 4013.Most of the other models have issues with Nand or Nand related issues but iPhone X small issues on that cases it can be fix with externaly . The mostly problem appears after water damage on Charging flex with vibration and upper flex with flood illuminator. I also fix that problem many times.This is the work that i have done makes you help to solve that issues.

Sounds like problem in SWI line the middle pin of the battery.

This is one of the common problem shown on the iPhone 8 Plus.I also faced that problem and i solved it.That problem is actually from the pin name display to MAMBA MSYNC CONNECTION pin problem.If you still stuck on that problem that is extremely helpful for you.Before doing you need some knowledge about micro soldering.Do that job carefully.

Use iTunes sometime the 3utool got some error and you try to restore by saving user data .That process sometime makes that error.Try full restore on that process the data will no longer acessable. Only the iCloud data you got.

The best way to discharge battery is one 4-5 v LED connect to battery still the LED off .I try on one of the battery very time ago.Hope this process is helpful.

Check the parts near the battery connector. Be sure that battery is charged or connect to battery connector properly.

That is the common issues that on iPhone 7 & 7plus series.That is the issues of audio ic the pin under ic is broken that cause.So simply it`s a hardware job need microsoldring skills.That have other issues shows with that problem.If you don`t have idea on repair this may help you. Speaker greyed out. microphone not working. videos recording stuck. no sound on ear speaker. all have common issues that related on.