Floor No. 20

You are at a 12 story building called ECE Bhaban. You have just entered into a lift which has took you to a mysterious floor, Floor no. 20. In fact, you have got stuck into the lift and there is no way out of it except unlocking a Mysterious Lock. In order to unlock it, you have to solve a Puzzle.

This is a companion discussion topic for the original entry at https://toph.co/p/floor-no-20