Navigation at the beginning can be confusing until one finds the highlighted red bars which indicate possible locations for exploration. In order to progress, one has to search dead bodies and perform violent acts on strangers.
Thanks to @VicariousE, I was looking for a place to enter the password for a locker. Then, I found a tiny box above the word "Enter Combo".
The clue to the last puzzle is kind of vague. Also, the TV screen is filled with many colours which can be confusing. Hint: find five numbers with their corresponding background colours. Two numbers appear in the purple field have to be entered.