For you to connect if your friend is there he needs to turn OFF bluetooth in his device. Then you should be able to connect.
I think that since your friend connected first, there must be a priority connection order in the Braven therefore his connection gets preference.
I suggest you press the reset button. Hopefully this should restore the Braven to default and remove all bluetooth connections info. Then connect (re pair) your device first. Then if you want your friend to have access as well connect his device next.
The user manual is pretty light on detail. If you have further questions contact the maker at the following
Here is a link to the user manual.