Is that Kindle detected as a removable disk when you connect it to a computer via USB cable?
If that still work you should be able to copy firmware bin file (that you download from Amazon's website) and trigger firmware install by holding the power button for 15-20s to force a reboot.
https://www.amazon.com/gp/help/custo...MQC26VQQMM8XSW
That would hopefully fix any files that thing you installed has modified.
As for what firmware is currently on your device: you either don't have 5.16.x on it or you don't have a PW2 but PW3 or newer since the newest firmware available for PW2 is 5.12.x.