[Fire Q&A, Help & Troubleshooting] Nazo:
So I didn't expect it to have the greatest battery life in the world. I'm coming from a Nexus 7 2013 edition (just wanted something cheap to carry around -- I'd be very upset if my Nexus 7 was dropped and broken or stolen in public whereas this $30 tablet won't exactly cause me to lose any sleep if it does, but I need to be able to read and otherwise pass breaktime at work) so I'm used to it lasting almost a week on a full charge since all I do is simple stuff like reading with a relatively low backlight even. I noticed my new Fire 7 is going down so much faster that it will surely be a problem (I guess 20-30% a day?) Now, of course, the Nexus 7 has a significantly larger battery. However, its ~5-7% compared to this thing's ~20-30% is not to scale. One big difference though is the Nexus 7 gets to run a clean LineageOS setup with a rooted Greenify (actually I have Xposed, but lately the module doesn't work without explanation. That's an issue for another time though.) The battery is purportedly a 2980mAh versus the 3950mAh in the Nexus 7, so at 75% the capacity I wouldn't expect it to get 1/4th the run time. I'm hoping Greenify can help. Unfortunately, Greenify is not working at all.

Firstly it seems you must manually grant a bunch of permissions for certain things. During initial setup it tells you to grant one and sends you to the settings, but it doesn't send you to whichever part of the settings it actually means for you to change. (I'm guessing something that isn't present on this thing's modified non-standard system settings app.) Now, they give you instructions on how to manually grant certain permissions via adb, but it doesn't mention that particular permission. It seems also that the accessibility service that it uses for hibernating isn't actually working because it pops up a message. However, that could be related to the more serious problem at hand: it doesn't work at all. When I press the hibernate button, it does nothing. Literally nothing. (Which makes me wonder if it's just saying that because of its failure when it tries to automatically hibernate.) Without root access obviously it is much more limited in what it can do, but it should still do something. The guide only has you grant DUMP, READ_LOGS, and WRITE_SECURE_SETTINGS. These are intended for features like accurate app state detection rather than basic operation though. I have no idea what it wants on initial setup since it's not specific at all.

Actually, I think it's not actually granting the permissions at all in the first place. I manually grant those three via adb as it says and pm doesn't say anything back. Regardless, Greenify is unable to do anything at all -- it never hibernates any apps even when run manually. I'm not sure how effective it will be without root, but I'd still like to get it working if at all possible. Still, it officially supports rootless systems, so I don't really understand why it's unable to do anything at all. Even the most basic functionality should work at least (though if it only acts as a task killer it may do more harm than good. Hard to say since I can't even get it to do that much even.)

Any idea what I'm missing?