Things to learn from this: Be careful when using HP-62xx PSUs or any other PSU with overvoltage crowbar to power devices that can act as power sources, such as batteries, DC motors with big flywheels that can act as generators etc. If the crowbar trips, the source will fry the resistor
It happened to me before as well, when I charged a SuperCapacitor bank (27V 300F) with another Agilent PSU.
This PSU did not have a protection resistor installed
The SuperCapacitor was hooked up and the PSU went to Over Voltage Protection and big smoke came out of it.
Turned out, that the big PCB traces for the protection burned away.
I am using this PSU now without the OVP.
Really, I think Agilent should have a big warning on the outside of the PSU, explaining the Crowbar installation, especially when there is no protective resistor installed. It seems they rather kill their own equipment and protect the DUT.
Yes, I also learned a great lesson at that time.