You have the old version of heater&thermocoupler (that's why there is a black cable) and, in consequence, you must have the old type of extruder PCB. Therefore I would replace all of the components - the hotend, the extruder PCB and the heater&thermocoupler.
If you need more info, please contact me via PM.
I'm in the same boat - I put in HotEnd V2 on my Gen 1 machine - and thought maybe Z had not done documentation for my black wire.
So where do I get a new extruder pcb? Heat and Thermocouple is readily available everywhere.
and maybe it would be an idea to clearly write on the online install instructions that Gen 1 machines needs new PCB & Thermocouple to use the V2 hotend.
Thanks for your suggestion.
Get in touch with one of our resellers to buy a new extruder PCB: https://zortrax.com/resellers/retail-stores/
You can also contact me via PM for more info.