So I'm trying to solder a power button onto my RPi 0. My issue is simple actually. I can't get the solder to melt onto the board. I've watched several videos all say the same. Basically to touch the pad with the iron then the solder to the iron tip and slide down fast. I tried this and either the solder just like evaporates or it beads up onto the iron or onto itself. I'm using lead-free rosin core solder 2.2% flux at about 350 C. I've basically melted the back of the pi which is fine since I bought about 15 because I assumed I'd mess up. Any insight as to why this is happening? I thought about maybe picking up some flux gel but in all of the videos I seen, none of those people used them nor had this type of trouble. Could it be my temps? I tried lowering them but it just doesn't melt the solder in that case.
EDIT: I've never actually had an issue soldering but I've also never soldered anything so tiny. Usually soldering for me was big boards for RC stuff.