the motor black lead as well as the battery black lead connect to the same point on the circuit board, a hole in the corner that requires a through bolt and a self locking nut.
I believe what you stated is incorrect. You are stating that both the motor black lead and battery black lead connect to the same point on the circuit board. This is not the case.
There are two leads that will connect with the negative terminal on the bottom battery.
These are:
-The black/negative wire from the motor.
-The black (& half white) wire that runs from the corner bolt on the circuit board.
Please see the attached photo as reference.
As info, I have a Type 4 but my guess is that these wiring connections are the same for all Types (i.e. 1 - 5).
Hope this helps anyone replacing the batteries for their CMM1000.