My iphone 6 is faded black from the corner. What should I do?

BTW my phone fell in water but everything still works fine except the cameras do not work and the faded corner

It's possible some water got in the screen. Is the screen actually faded or the corner of the device?

you may have to get it replaced if you want your cameras to work and the fading to go away. For future replacements, consider purchasing Apple's insurance program. I think you pay around a $100, then if you need to replace it, you pay another $50 or so. That way, you don't have to pay for a whole new phone.

take it to an apple store to see if they can do anything otherwise.

Contact customer sevice

Get android

It's getting damaged and more you keep it turned on, more it'll deteriorate. Turn off the phone, take the SIM out and keep the phone in raw rice bowl for 2-3 days. If the camera is not working, it might be possible that the chip might be damaged.