That’s for sure. It’s also true that the big stranded wires coming off the motor take solder like shit. They’re really a nightmare to do joints with and you really need to know how to solder if you want to reliably connect them.
Anyway, I consider myself lucky and I hope my post could help someone not to throw away a motor or a Vesc 
i used my dremel to take of the coating and used some old copper wire strand from my stereo and coiled it around the silicone wire and the phase wire. i will probably reopen it and make it smaller.
I’m glad you found your issue 
This is an awesome trick! At adds a lot of mechanical strength to the solder joint and makes it last longer in stressful situations. The resulting joint however is stiffer and I had too little of phase wire coming out the motor to do this, so I had to do the old “twist the wires together and hope for the best” thing to my motor. We’ll se whether it holds fine or not: if not then I’ll have to get myself a new motor…
I’m glad too, and I’m also glad that the issue was in the motor and not in the vesc. This helps a lot as the money for the build were already very tight 