Tutorial: Root/Unlock Fire Stick 2 (2nd gen)
A more comprehensive tutorial on how to flash ROM with amonet, and unlock your Fire Stick 2 device. This will allow you to reboot device into TWRP and flash with custom Android O/S of your choice (i.e. Lineage).
Unlocking an android-based device, like Amazon Fire Stick, allows for root access and complete control over all aspects. You can then uninstall bloatware, modify permissions, change mac address/bt mac address (via "idme"), control your device remotely and even change the device's serial number.