To correct this issue, first disconnect power to the Blackbox. Next, plug your handset into the Blackbox USB jack and then reconnect power to the Blackbox. Push and release the Handset power button if needed to power ON the All Road. After a few moments the Handset should display normal CB standby mode.
Connecting your Handset to the Blackbox will re-establish Bluetooth Pairing.
If the problem persists, there may be something in your setup that is interfering with either the Blackbox or the Handset's ability to establish a Bluetooth connection. The first thing to check is going to be your power setup.
The ideal setup is to connect the wiring for the 75 All Road's Blackbox straight to the 12V battery. When there is no Bluetooth connection, the Blackbox will enter a low-power state. In this low power state, the Blackbox would take months to drain a healthy battery.
Try plugging the USB handset into a different USB port if you're not using the 12V adapter. If that doesn't work, try using the 12V adapter. If you are using the 12V adapter, try plugging it into a different 12V port. If that doesn't work, try using a USB port. Make sure that your USB port is capable of 5 Volts and 2.1 Amps.