Mine was acting real glitchy and laggy also when on steemit.com, my battery would fall on its face and I could watch the percentage drop every second. After a new battery, my iPhone 6 runs like a champ, why spend $7-800 on a new one when it cost $30 and a little time and patients to get the existing one working fine.
Good luck with your sons phone. 👍🏻👍🏻
As a father myself, we are always Superman to them, just at times we are Clark Kent 😎