Hi. This is not really a reply to my query. I received the same response from B&D - a reference to their manual - which is why I posted here. Inside the 36v battery are three 12v 12ah batteries connected in series with wires, one of which is a "fused" wire designed to melt if it sees too much amperage (like if wires got crossed) so the batteries do not overheat or explode. My wire melted due to severe overstress of the motor. The batteries all test as good. So I need to install a new "fuse," and want to make sure it is not too small - burns out all the time - or too large - batteries explode if the wires short. I could find this by trial and error and keep putting in increasingly larger fuses. But if anyone knows the answer to this query it would solve the issue for me.
This information is not in any manual I have been able to find online.