Take it right back to the store.
I second that. No point in a customer tolerating an obviously faulty device, especially one that could cause
really bad stuff to happen. Take it back. You might want to explain your dissatisfaction and why you're dissatisfied.
"The thing could have blown up in my face. Can I at least get money/cost back?"
Be sure if other customers are present to speak clearly but calmly and without obviously raising your voice, keep it low key and as much in a
professional tone as you can muster. I would gamble that the store will grant you money back immediately and perhaps even offer a bit more to retain your business.
If they do not, walk away and do not ever do any further business with them. If someone asks you if you recommend them, you do not and can offer a summary of this as to why you do not. Do not
bad mouth them but if you're asked you can at least offer that the store in your opinion is not one to warrant your patronage.
On the other hand if they do, enjoy a great store that places its customers first.
Tell everyone to come shop here. Or you might not, keep all the good to yourself.