I let my iPhone charge, and after about 5 minutes, it shut down and became very hot, unable to boot the OS. I removed the charging cable, and eventually, it booted up. However, once the OS loaded, the phone became extremely laggy and almost unusable. Here's a scenario: I set an alarm for 10:30 AM and received a time-sensitive message from the Pillow app. After the phone booted up, the message kept notifying repeatedly, causing the phone to overheat and laggy.