PS4 controller light flashes blue then the controller turns off

This isn't an overly big issue. The flashing blue light simply means that there is a syncing issue between devices; either the controller and the console (in this case, your iPad), or the controller and a charging station.

The easiest solution is to reset it using. To do this, there is a small hole on the back of the controller. You can use a toothpick or a paperclip to press the reset button, then resync it.

Using a cord to connect it to your device is also a good way to reconnect it, though obviously not really an option (that I'm aware of) for your iPad.

However, you can boot it using "bluetooth mode". Once you reset it, hold down the PS button, and the "Share" button. Make sure your iPad also has bluetooth turned on, and it should hopefully appear in your available devices to be paired.

Sounds like it lost the pairing, but it could be something else.

Regardless, resetting the controller might fix the issue. When you flip the controller around, you should see 4 screws. To the left of the upper-right one, there's a little hole where the reset button should be. Press the button for 5 seconds with a paperclip or something similar.

Remember to pair your controller with your iPad again afterwards.

The official Sony documentation is here: https://support.playstation.com/s/article/DualShock-4-Troubleshooting

See step 3.

I had the following symptoms:

• PS4 unused for 6+ months
• When pressing the PS button on the DualShock 4, the LED would blink a number of times with a blue light, then stop blinking.
• The controller would not connect to the PS4 if the PS4 was ON.
• The controller would not connect to the PS4 even with a USB cable connecting the two.

None of the solutions found on the internet would help.

Solution: Charge the controller for 30+ minutes. After that everything was working again. Apparently the controller was out of juice, but had enough juice to blink the LED.

TL;DR: Try charging your controller first.

Inshort 1. Connect controller via USB to ps4 2. Press and hold power button on ps4 until u hear second beep this turns off the ps4 3. After a minute or two press and hold ps4 again to listen second beep. This launches safe mode 4. Then u can connect the controller in safe mode. ?