luifmendes , Stop charging or powering up your device until the liquid damage is addressed correctly, as you could be shorting out components inside the phone. If you are sure warranty is not valid, You really should take care of the corrosion that is happening inside the phone from the water damage as that could be your problem. A tear down link for your device Link #1, disassembly guide will enable you to get inside the phone to remove the damage/corrosion caused by the liquid. Use the 2nd link as a guide/instruction on how to clean/repair the device from liquid damage. If camera continues to give problem try a factory reset and if still issue replace camera. Good luck.
I hope this helped you out, if so let me know by pressing the helpful button.
[guide|29206]
[[Electronics Water Damage]]