How do I get upstairs?

Hint 1 of 5:

It will be a while before you can take the regular door to go up.

Hint 2 of 5:

Have you heard about any other exits from the basement?

Hint 3 of 5:

You should go into the dungeon cells to find someone who can tell you where
another exit can be found.

Hint 4 of 5:

Then you know you need to closely examine the suit of armor.

Hint 5 of 5:

The right arm looks a little loose.