Chosen Solution
makes charging beep every 12 seconds, won’t turn on, won’t sync
Most likely faulty battery or screen. Try replacing one of them first. I’d probably start with the battery then screen. Parts shouldn’t be too expensive. You can get the screen from here: iPhone 4 (GSM/AT&T) Screen Replacement guide for screen: iPhone 4 (GSM/AT&T) Screen Replacement You can get the battery from here: iPhone 4 Battery