Used Samsung Galaxy Core Prime totally broken? Worth replacing bad battery, or phone doomed anyway?

[Android Central Question]

Since I bought a refurbished Samsung Galaxy Core Prime a couple years ago, it, at times, randomly behaved as though the Back key had been pressed. The virtual keyboard would disappear, or the app I was using would close. I think sometimes it would go back a page in a browser or app as well, but I can't remember for sure. It was mostly the first two things. It was as if a mischievous phantom were pushing the Back key. (Or, perhaps I mean the Menu key? I think it was the bottom left key.)

Additionally, the phone intermittently shut down or froze, requiring a restart. It also drained energy quickly; it could easily die from using mobile data for 2-4 hours total while I ran errands for 7-9 hours (as best I can estimate with my poor sense of time). It would warn of 3% power or less and shut down; then, I would have to wait for it to fully recharge before I could restart and see anything on the screen other than the charging battery icon.

Now, this was with a new Samsung battery that my friend had ordered for me, to replace the one that came in the phone, which was even worse. I had learned a few tricks to prolong battery life, such as putting it in airplane mode when not in use and turning off notifications (since then, I’ve learned more tricks, for future use); they helped some, but not enough, so I had to plug it into an external battery pack in my purse every time I went out.

For its last few months, the phone shut apps and virtual keyboards more and more often. During the last week of its life, it was hard to get anything done; an app or keyboard would only stay open for about 15 seconds or less before crashing. Finally, the phone froze, then its screen went black. It wouldn't restart. My friend tried a factory reset, but no go. Then he removed the back casing to discover the battery swollen, with a convex front and back, like a food can contaminated with botulinum toxin.

So, was the bad battery the cause of these problems? Or is my phone broken, and it would just be a waste of money to buy another battery?

I'd like to have this Core Prime phone at home and as a backup, and to add a Lifeline smartphone to use when I’m out, so that I don't need to keep cleaning my phone to use while I eat meals or work on the computer while snacking. (I’m somewhat of a germaphobe, but it’s also sensible to eat with clean hands.) But, I'm on a tight disability budget, so I don't want to waste money on a battery that only fits this phone, if the phone is completely dead/broken or will keep doing a constant "phantom Back key press," such that it's unusable.

Thank you for your help. (Please pardon the verbosity; I wasn’t sure I was using the correct terms, so I thought it best to describe in more detail.)

 

[Rukbat]

One of the problems is your use (or should I say misuse) of the battery, running it until the phone shuts off. Lithium batteries are not deep-discharge batteries. They last longest if you keep them between about 40% and 90%. Letting the battery drain until the phone shuts off can kill a new battery in a couple of months. (A swollen battery is a sign of a bad battery.)

That said, the phone sounds as if it started out with problems. If it were mine, I'd replace it with a new phone. (Not a used one - one that comes with a warranty, and that no one has misused yet.) About the only reason I can see for the "phantom touches" when it's not in your purse would be a bad screen. If you can't afford the best, go for a cheaper line, but don't buy someone else's problems. (Some people sell their phones every year when they buy new ones, even if they're in perfect condition - but some, when the phone just doesn't pay to repair, sell the phone as if nothing is wrong with it - and the buyer gets stuck.)