I have received the product LM2596 DC build-in box purchased from amazon and the box which is build in is not transparent so I can not see the voltage screen. The parts of the box has a brown film that I am not able to quit it.
Could you please tell us your order ID or the ASIN of the product?
It is better that you can send us some photos of the problem details.
With your help, we can find a solution more effectively.