Hi this is an indication that some water got inside the phone. The way to fix this is to place the phone in side a paper bag with about 2 cups of dry uncooked instant rice and cover the phone with the dry rice.
This process takes about three days to fully wick out all the excess moisture. Make sure the phone is turned OFF during this process!
This will work about 85% of the time on your iPhone;-)
In any case, I will stick with you until this is complete.
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