paring aa Braille display with iPhone

Hi. Does anyone know how to pare a Braille Sense u2 Mini with an iPhone 6S+? I turn bluetooth on on the display, enter terminal for screen mode. When I go to braille in the VoiceOver settings, select Braille Sense u2 Mini, type in the pin thing, and select pare. But for some reason, the braille display seems frozen, because it won't let me enter the pin on the display. It just says terminal for screen mode. When I try to type in the pin, nothing happens. Same thing when I tried to connect it with my iPad.
Could the braille display be broken? Thanks.