All the auto-dark helmets have sensors on the front that have to be exposed to the arc to go dark. If the helmet only has two sensors, it might not get exposed to the bright light of the arc if you are welding in a deep groove. That usually when I see a problem.

Your helmet might have a bad sensor. Like any solid state device, if they are weak from the get go, they typically fail in short order. If the solid state device is "good" it can last for years without a problem.

Any company that won't stand behind their product line is a good company to steer clear of.  InstaPark may be the brand or model, but who was the manufacturer? Chances are it was produced in China and they just slap their decal on the box. It is a story we see all too often.

Interestingly I heard the same complaint from an engineer in Russia. He said, "We don't build anything in Russia any more. Its all imported from China and its all junk!" Sound familiar?

Best regards - Al