You probably have something wrong. As seen in the pic below, make sure the positive lead (usually green or red) is on the lower left, negative lead (usually black) is on the upper right. Check the wiring of the pack, make sure it is series wired, and check the battery orientation required in the holder, as sometimes these are different than the orientation of the games original holder.

The diode in the holder is not needed. The game already has a blocking diode on the motherboard, test and make sure it is good. I recommend cutting the diode on the external pack out and replacement with a jumper wire.
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