Which player you need
Some players are listed in the Amazon Appstore and install in one step. Others are installed using Amazon’s own sideloading route, which the device supports but switches off by default.
We confirm the right player for your exact model before you install anything, because what is available in a given store changes by region and by the age of the device. Send us the make and model and you will get a specific answer rather than a list to work through.
Switch the unknown-sources setting back off once the player is installed. Fire TV devices also benefit from being restarted occasionally — they are left on standby rather than switched off, and a restart clears up most odd behaviour.