The Mayfly’s bee footprint was originally set up to only power modules that require moderate current supplied to the Vcc pin of the module, such as Xbee RF modules (900Mhz and 2.4Ghz), Bee wifi, and Bee bluetooth. There are even GPS modules with the Bee footprint that work great on the Mayfly. Then when we started using 2G and 3G cellular modules from SODAQ, they have their own separate JST sockets for connecting them directly to the LiPo battery, thus supplying sufficient voltage and current (they require ~3.7v and up to 2A). But other brands of cellular boards, like the Digi 4G board, don’t have the external power connection option, so the only way to power them is through the Bee header on the Mayfly, which is why I added the SJ13 option on the latest v0.5b Mayfly boards. So just cut the small trace that’s connecting the center pad of SJ13 (labeled BEE_Vcc) to the 3v3 pad, and put a solder bridge joining BEE_Vcc to the pad labeled LIPO.