Unisen KP-810-25BTT User Manual page 8

An window like below will popup indicating that system is searching a devie to
add...
Turn on unit by moving the power switch to ON, press key "Esc+K" reset it
(about 5 seconds). Bluetooth iPazzPort and Bluetooth Keyboard will appear
in the window. Select it and click "Next"
Bluetooth Reset
Then you are requested to input a pass code for your device, please do type
the code with Mini bluetooth keyboard, then press Enter
Bluetooth
keyboard