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 [https://www.youtube.com/watch?v=icAxjx1JG_Q&t=75s|work] that i have done makes you help to solve that issues.