Sorry Rhys, it looks like some shipments got packed without the extra fuse. Also some were packed with the fuse in the box/bag, but outside of the toolcase. Did you check the box?
I’ll drop a fuse in the mail for you if you don’t find it.
Regarding Android versions: the app presently targets Android 4.3 and above. A lot changed between 4.2 and 4.3 that makes 4.2 quite difficult to work with (the BLE implementations vary by phone manufacturer). I’m fleshing out features and working on stability before I try to backport anything. I can’t promise the app will work for 4.2 on all phones. With a Galaxy S4 I am pretty sure you can upgrade Android… would that be possible?