My phone is dying at 90% and i dont know why

[Android Central Question]

I've had my galaxy S3 neo for 2-3 years
And for some reason it started dying around 30% and it's getting worse with time
I -replaced the battery
Nothing changed
-changed the charger
Nothing changed
-factory rest
Nothing changed
Of course the only thing left is the phone itself but the golden things in the phone have no sign of any damage
No the phone doesn't look it's percentage after shutting. It just doesn't restart until I plug the charger again
And when the shut down happen the screen sometime glitches with some lines ob the phone that are juts brighter than the rest of the screen
That stoped now as it shut down instantly
It does drop to zero sometimes if I take the battery out a and in and out a few times but usually it stays at 90%

I've literally been stuck to the charger for a while (which is defeating the goal of a mobile) so is there anything to fix this?

 

[B. Diddy]

Welcome to Android Central! Where'd you get the battery from? There's always the possibility the battery is also defective, but considering how old that phone really is (it's 6 years old), I wouldn't be surprised if other hardware components were failing.

Does this happen in Safe Mode as well? https://support.t-mobile.com/docs/DOC-32821

 

[Mooncatt]

Welcome to Android Central! Where'd you get the battery from? There's always the possibility the battery is also defective, but considering how old that phone really is (it's 6 years old), I wouldn't be surprised if other hardware components were failing.

Does this happen in Safe Mode as well? https://support.t-mobile.com/docs/DOC-32821

Ditto , though I'd still lean more towards the battery. A phone that old wouldn't have any current manufacturers of the battery. Even the third party battery companies would've stopped making them years ago. Any "new" battery you find for it is going to be a crap shoot and the odds will only get worse. Even sitting on a warehouse shelf, batteries will degrade over time. I'd be surprised if there are any good batteries left for that phone.

On the hardware side of things, it's just simply time for an upgrade anyway. Even if nothing is technically wrong with it, it's not hopping to be able to run many apps and it's no longer supported to even get security updates.