Apple India — iphone 6s not working

Address: New Delhi, Delhi, 110014

I had purchased an iphone6s on 16th may 2017 last year.
There was an issue with the motherboard of the phone and i got a replacement phone from service centre which they claimed as a new one that has been provided. Now within 5 months again, the phone has died.
If we say that faults can happen to any machinery, does your replacement phone dont last even for 5 months?