The Samsung Galaxy Note 9 powers off or restarts by itself.
The Samsung Galaxy Note 9 powers off or restarts by itself.
To address the issues you've experienced, it seems your battery loses capacity quickly once it drops below 20%, and the charging process behaves unpredictably. The fingerprint scanner occasionally fails, though not severely. Recently, using the flash for extended periods caused your phone to vibrate excessively and eventually reset itself. The problem worsened when the scanner malfunctioned, forcing you to unlock with a pin and then experience frequent reboots. After researching, some users resolved similar issues by disabling the fingerprint scanner as a security measure. Replacing either component might help, but it’s unclear if the core problem lies elsewhere. You’re considering a phone replacement, which could be worth exploring if the symptoms persist.
You might consider swapping the battery, though it’s possible it won’t make a difference. The decision depends on whether it’s worth investing in a potential fix. Upgrading seems like a good idea, especially if you enjoy the Note model—you’d likely prefer the S Ultra lineup, which builds on the Notes and even adds a pen.
Without opening the phone, it’s hard to confirm, but you mentioned the battery is likely the issue. All components connect to the battery, so poor voltage or a weak link can cause problems. Swapping the battery usually takes about an hour with a professional, though it requires patience to remove the adhesive. If the phone was dropped, exposed to moisture, or had too much water, the battery becomes a more probable culprit. The motherboard could also be affected, but Samsung doesn’t offer diagnostic tools, so replacing the battery seems like the most practical solution. Your phone is definitely one of the best I’ve seen.
The main issue seems to be the battery. If I find more similar problems, I'll probably focus on replacing it instead of buying a new phone. @Brando212 I haven't done a factory reset yet; most discussions suggest it, but the problem persists and there were no updates around then. I haven't installed any new apps recently, so I might decide later whether to replace the battery or switch devices.
I’m finalizing this thread and making the necessary updates. I swapped out the battery, fingerprint scanner, and charging port. I discovered in Samsung’s diagnostics you can check the scanner, which revealed 3 failures out of 7 tests. It seems the fingerprint issue was likely the cause, as the phone would work well with a battery above 20% before the shutdown. I changed the charging port simply because I was already using the phone daily. About a week after the replacements, all problems disappeared—thankfully only spending $50 instead of buying a new device.