It's completely anecdotal but three similar model phones breaking in exactly the same manner at exactly the same period in their lives was enough to put me off Samsung for good.
It's been some years since and I've seen Samsung in one scandal after another. Like the time they had an entire range of flatscreen tvs break because they put the transistors too close to the cooling plates, fixing it by moving the transistors but replacing the $0.5 piece with a Samsung produced transistor which they've never sold, making repairs nearly impossible.
I blame Android's continued bloat creep[0] for that slowdown though. My brother had S3 before, and so does my SO, and they were all becoming less and less usable with time and each system update...
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[0] - Is there an official term for the phenomenon that software bloats expands to cancel out any improvements in hardware?
But to be fair I don't do system updates so I don't experience the gradual slowdown that comes with increasing software bloat.