Chosen Solution

The controller was fully charged but when I try to use it wirelessly it turns on and then 2 seconds later turns off when fully charged

Instructions To connect or charge the controller, use a micro USB cable. Compatible with PS4 system software version 3.50 or later. This controller can communicate data to the PS4 system through a USB cable. For details about the settings refer to the user’s guide: https://manuals.playstation.net/document….

Try pressing and holding the reset button on the underside of the controller for a few seconds. If that doesn’t work it could need a new battery.