Answer to "phone constantly shutting off when using the camera"could be a bad app or camera mech issue. first, delete the apps that could be the problem. if that doesnt work do a factory reset.
Answer to "My phone keeps turning off"Replace the Battery. probably has the original battery. if it hasn’t been dropped or water damaged. start there.
Answer to "My galaxy note4 is completwly unresponsive...Help"if it hasnt been dropped or water damaged, First check the Battery. Replace. Im thinking its the original battery that came with phone or an old replacement battery. start here