I have tried: taping them together, hot glueing them together and ziptying it right to the frame to prevent jiggle.
All have failed.
Right now, when I reconnect them and apply pressure, I can’t even get the engine to turn on anymore. But the speedometer still works and that signal is sent through the engine cable too.
Recently, sometimes the engine rear wheel barely rolls when I roll the bike backwards.
There are no ebike repair stores in my city.
Do you want the connection to be permanent? You could cut off both connectors, strip the wire and solder them together. If not permanent you could replace the connectors with a better pair
Inside the cable there are 8 or so smaller wires. I don’t have the expertise to do it, and I’m not sure who I can find in my city who’d do it. I’ve been planning to call you electricians and ask.