You cannot. I tried the same with Flipkart. There is no return in Flipkart. That’s how messy things are in India. I contacted Flipkart regarding the weak vibration problem. They asked me visit service centre. I did. They checked my phone and compared it with another Nothing phone, which obviously had similar sh!tty vibration, and said all okay, NTF.
Sell that piece of crap. I will file a lovely complaint against flipkart at consumer forum anyway. Just for fun. But just selling it is much easier as there will be no time waste.