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Hi recently my phone was dipped half(camera side down) into the ocean while the phone was in my shorts pocket. i pulled it out and it was working fine that time. but rear camera and front camera was not working at that time and filled with fog so I switched it off. i opened the phone(only lifted up the screen after unscrewing the pentalobe screws) and cleaned the water drops with tissue and left the phone in jar with silica gel pouches for 2 nights. now front camera is working fine but the rear camera and flashlight is not working at all. kindly tell me what should i do. Not thinking of taking it to apple service centre to avoid high charges.

It may be an issue with the logic board of with the camera modules. Try removing and reinstalling the modules iPhone 7 Plus Rear-Facing Cameras Replacement