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I bought this iPhone XS from someone and he didn’t tell me that it has liquid damage. Everything on the phone worked fine and I decided to open the phone to see what’s wrong with it. The iPhone have red water indicators on the screen and after putting 50% ISP on the infrared light and clean the charging port cable the power button some times wouldn’t work and it only works when I press it with the lower volume button. After cleaning the charging port cable that I thought was the power port cable the phone would not power on and when I connected it to the charger it says connect to iTunes for resetting. I think the phone had a little water damage because I couldn’t hardly see any corrosion and the screen is working fine. Only front camera portrait mode, face ID, and the power button are the only once not working. Power button some times work and some times not working. Any help on how to make the Face ID and the power button work would be apricated

If the Face ID will not function make sure the cables are correctly seated. If it still doesn’t work then you have a damaged Face ID module and it won’t work again unless you take it to Apple for Out of Warranty Repair. I don’t know about the power button but if thats not seated properly either then it may be a logic board issue. And most of the time you need to use a microscope to see if it is or not.