Any time that a human is involed in any type a prduction on any product there is always going to be the chance for human error
Hey I found it....
so I set the mah lock out at 4200 mah
Looking at both sides of the story, you were warned not to do this numerous times. You cannot blame the charger. It did as it was told, "ignore all signals of peaking until you have put 4200mah into the pack." It's like someone said, a bucket can only hold so much water. The battery cannot continue to be charged past it's limits. If it was the cells fault, then every manufactured cell is a "bad batch" because any could blow when you continually charge them with a long lockout on.