x2 Heat the ring terminal just below the eye hole on the back. then put the solder on the other side of the ring terminal it will melt and flow into the wire. The best way to do it though is to crimp it and solder it.Don’t bother smashing or crimping itYou need to solder it; you need more heat, lots of heat
Do not heat the solder, heat the connector until the solder melts into the wire
A 1/0 connection will take lots of solder