iPhone 14 IP68 // dead pixel drama

Hi, so I got an brand new iPhone 14 for Xmas - crazy gift, I know - but the fun began after discovering a dead pixel, which iSpot (Polish premium Apple reseller) confidently refused to find existent (thrice). Then after using the consumer rights provided by the national law they asked if we wanted to (1) change screen (2) get new phone (3) money back.

Considering the importance of a smartphone in daily life I asked for a new one. After all it has be worth its cost, and not be worse off for the same price. So they accepted. Then a few weeks later after being notified to pickup the phone, we picked up the phone to only find out they just changed the screen.

However now I am not sure of its water resistance - hence asking for a new device upfront, as factories vacuum-seal the device and make sure it follows IP68 requirements. While in reality, this serviced device is not anymore equal to a brand new iPhone 14 with no prior services. And for my usage it WILL be put through water on a weekly basis, and I have to rely on it working. Which is fair, when buying a new iPhone.

Is there a way for the store to show it is just as good as a brand new phone and promise its functionality by putting it through actual tests, water and certification to have a reliability assurance?