I'm not able to connect my phone/tablet via Bluetooth.

Unplug the power cord of the receiver for at least 2-3 minutes.

Go into Bluetooth settings of your device and "Forget this device" or "Unpair this device".

Plug receiver and set the input to Bluetooth. Wait until you see "Now Pairing..." Enable (turn on) the Bluetooth function of the Bluetooth-enabled device, and then select this unit from among the devices displayed.