Powerbeats pro not connecting after device was forgotten. The device just keeps blinking white light

Please , try this first --> If you can't connect to your wireless Beats product

Then...

Hold down both the power button and the volume down button for 15 seconds. When the LED indicator light flashes, release the buttons. Your earphones are now reset and ready to be set up with your devices again.

Reset your Beats earphones - Apple Support

Tried this for several hours. Still not pairing.

If you are unable to get the Powerbeats Pro reset or into pairing mode, by using the link provided, then you need to use the Get Support link at the top of the page here to contact Apple Support. If you have an Apple Store close by, make a Genius Bar appointment to get help from an Apple Genius. They will explain your options. Genius Bar Reservation and Apple Support Options - Apple

You will need to put the device into discovery/pairing mode, then turn on Bluetooth on the iPhone if that is the device you wish to pair with. See this, Set up and use your Powerbeats Pro with an iPhone, Mac, or other device - Apple Support