To reset the device to its factory settings: 
Power on the speaker. While on, press and hold the power button down for 15-20 seconds until the speaker turns off.

Now that the speaker has been reset, make sure to remove it from your BT settings if it was once paired to other devices as the BT memory has been reset as well. Once you turn the speaker on again, it should automatically enter into pairing mode with a flashing LED. It should pop up on your discoverable devices under your BT settings and connect within a few seconds.