Hi There is not a version of Firefox for Android available for the Amazon products, but there is a way that you can download it and use it on your device. In the system or settings app on your device, you will need to find the setting to allow the device to install software from unknown sources. You will then need to consider carefully and download the file for the version of Firefox for Android you want to use using your mobile device. * The full release version of Firefox for Android (available [https://ftp.mozilla.org/pub/mobile/releases/42.0.1/android-api-11/en-US/fennec-42.0.1.en-US.android-arm.apk here]) will not automatically update. You will need to check for updates manually from within the app. * Firefox Beta for Android (available [https://ftp.mozilla.org/pub/mobile/releases/43.0b7/android-api-11/en-US/fennec-43.0b7.en-US.android-arm.apk here]) will not automatically update. You will need to check for updates manually from within the app. This is not a finished product but is more stable than Firefox Aurora for Android. * Firefox Aurora for Android (available [https://ftp.mozilla.org/pub/mozilla.org/mobile/nightly/latest-mozilla-aurora-android-api-11/fennec-44.0a2.multi.android-arm.apk here]) will automatically update, but is a less polished version of Firefox Beta for Android, so may contain some bugs. (There is an earlier version, Firefox Nightly for Android, but this is significantly less stable and is very much an unfinished version of the browser.) Once downloaded, it will either open automatically, or you will need to open it using a file explorer type app. I hope this helps. This is a very non standard fix, but I hope that this helps.

The Release and Beta channel builds installed manually and not by way of Google Play do not get updates at all. To update you will need to manually load new versions each time. Nightly channel has later versions (currently has 45.0a1) and not earlier versions as earlier implies older.