Answer to: Why doesn't my iPhone turn on?Have you heard of the rice trick? Put the phone in a bowl of dry white rice for 24 hours. This helps to absorb the moisture out of it. Then connect the power cord and try to turn on with it plugged in to a power source.
Answer to: Why does my iPhone randomly shut offI agree. I just ordered and changed out the battery for the same issue. Problem solved and working great!! Warning: If you order the battery, also get the suction cup and follow the instructions very carefully to avoid damaging the tiny ribbons inside. It does take a steady hand and about an hour but it is very doable for under 30 bucks!