Without a second thought, you open the door.

You open the door, and you die in a hail of poison arrows. The arrow slits weren't even well concealed. Even a cursory glance would have helped.

Nice work, idiot.

Now your mom is going to cry about her husband and her child, and your little brother will be sent to find the helm when he is of age, and will probably die here too. Hopefully, he's smarter than you.