Amazon India - Sold used mobile as new

I'm writing to draw your attention to a critical issue involving a purchase, I made on Amazon platform. On **.**.****, I ordered a “New” Samsung Galaxy Note**+ from the seller, Shri Shyam Mobile Hub on Amazon India. However, after *.* years of product use, on **.**.****, the phone accidentally fell in a water tub for a few seconds, causing the mobile screen to flicker and gradually shut down. Upon a close investigation of the mobile, I discovered there was moisture formed on the camera lens and astonishingly, the IP** rated mobile's rear panel was merely loose and came off the hand, with little or no effort resulting in water damage, ruining the display completely.
When the phone was taken to the Samsung authorised service centre, Shyam Electronics Ambattur, on **.**.****, the service centre informed me that, the phone was used previously and that the actual purchase date was on **.**.****, along with previous repair information on the phone and owner details.
Therefore, based on the information provided, it is evident that the phone was unable to withstand water damage for more than a few seconds, because the IP** rating was compromised during the last repair, which in turn caused display damage. As a result, I was required to pay an additional Rs. **,***/- for the screen's replacement.
Please take note that, when I bought the phone, the warranty was already null and void.
Despite several attempts make them understand my point view, the Amazon customer’s service agreed only for “Return and Refund” option and are not willing pay the repair, nor willing to pay any compensation for their fault neither apologetic for their deceptive and unfair practice to have cheated the customer with used product, for which whole premium was paid in single shot.
It’s been almost * months since this issue, now I feel only legal actions can be help me resolve this issue.
I please request Voxya team to help sort out this issue in a best possible way.
Many thanks in advance.