One way I avoid indexing is to not have too many books on the device at one time. Maybe the most I’d have on it is 10-15. I routinely go in a delete books from the device. As your problem seems to be the battery you might try this:
https://www.ifixit.com/Guide/Amazon+...lacement/99289
Seems to be a fairly easy task. Battery 35 bucks, tools about 10. I have a Kindle Voyage with a battery at probably about 50% that someday and I’ll do this repair vs chunk it. You may find other options for replacing the battery with google.