Had the same problem with the pass through for my 401. Luckily I was right there and caught it after about 30 seconds. I've only had it for less then a week so I notified the supplier and he told me to ship it back, and he will replace it.
Those things get really hot, really fast. After that 20-30 seconds I could barely pick up my PV so I just unplugged it. I guess that's one way to do a dry burn, if you have automatic batteries
Danger Will Robinson.....Danger.
There is obviously a huge potential for fires if these things malfunction, so people need to be really careful and pay attention when using them.
This is not the first post I've read about problems with pass throughs, so maybe suppliers need to get on the manufacturers about quality control.
All it will take is one fire caused by a pass through, and the negative publicity will crucify the PV industry.
Ez