Aerospace engineer

i would like to come under highly responsibility to tell all about the small problem we got last few days ago before we try to test our first VTOL 260 as well as is still in processing , we had been used pixwhak cube 2.4 as MC (Micro controller) as brain of the whole circuit system all functions were running correctly unless the battery percentage doesn’t appear on the screen cause the power module 2.1 when connected burn the second part where power modules supposed to connect so that now we are remained the first port connector which is only work, hopefully i would like to ask what cause damage the second port while the installation through the battery was smooth?