You may need to swap the positive and negative wires over on the connector to use on one of Kite’s Circuit Swords or on the Adafruit Power Boost 1000c.
Ensure that the Positive (red/+) wire and Negative (black/-) wires on your megabat match up with the connection you’re plugging in to. Other wise you WILL fry the charging circuit or worse.
Also check and then check again its correct before swapping the pins AND plugging anything in.
Its a simple task, so don’t worry! You just lift the plastic tabs on the connector to remove the wires and swap them. Below are some pictures illustrating how to accomplish this, Thats it! nice and simple!