I phone 12 pro - Phone got damaged between one month

I bought this phone on **th june **** from cashify thane branch and on *th of july **** the phone got dead i bring the phone to Cashify kalyan branch to check the phone the technician said its water damaged even there was no evidence of water inside the phone it was only some white mark at the charging point and the technician said whole strip of motherboard got damaged when apple commit i phone is water proof