Great job by
@ilovejedd!
Unfortunately, there is no customer firmware 5.10.1.3.
As we can see here
https://www.amazon.com/gp/help/custo...deId=200203720
one can download and install 5.10.2 or 5.11.1 only.
It means that after installing customer firmware jailbreak becomes impossible if lost.
So be careful and do not forget to reinstall the hotfix before every update, otherwise you can lose jb.
In the meantime, we have several reports that users do not install customer firmware, staying on the factory fw, and experience no problems, at least CoolReader works fine.