This is the source code of my one-weekend Jawbone UP2 hacking session from late 2015. Here's a link to the blogpost: UP2 Reverse Engineering.
I'm releasing the source code now because I've received a few requests reporting that after Jabowne went out of business they shut down their servers, making it impossible to use the UP bands.
Unfortunately the code I wrote it's a mess (it was just a hack after all 😁 ), and I'm not sure it's still working because my UP2 broke, so I cannot work on it anymore.
I've updated the Android project to make it buildable with the latest version of Android Studio (3.0 currently), so it should compile out of the box.
I'm sorry I cannot provide more support to anyone who's interested in this project, but if you're looking into hacking the Jawbone UP2 I'm sure this will be of some help.
Stefano