I have just upgraded my 4G X27 gemini to Android 8.1 (early 2019 image), and now have the battery draining in a small fraction of the time it used to. Is there a fix for this, or a way to return to Android7?
While it may not be of much help to you, my own Gemini (which happens to be a 4G X25, but as far as I know, the hardware is virtually identical) runs fine on 8.1 (as far as I know there's only one version of 8.1 for it, and thus I suppose we both have the same version), so I can at least confirm that what you are experiencing isn't normal.
As far as I can recall, beyond some minor initial issues (which seems to be pretty common for new Android versions on any phone) I didn't get any battery life issues. However, unless someone more knowledgeable than me chimes in, and since you couldn't find any other post here on OESF, addressing the issue, you might end up having to back up everything, do a factory reset and reinstall everything again.
One issue I did run in to when upgrading to Android 8.1 on my Gemini was that I never got my e-id to work again, but that's a Swedish thing, so I expect it wouldn't affect you. I hope you will be able to find a solution.
