Go inside Emerson Express and after a fight with Randal's boss leave the building. Pick up the broken radio.
Go to the pawn shop and talk with Mel. He wants to buy something from Randal. Leave the shop and go to Randal's apartment (by using subway).
Go inside the house - Marconi is still waiting for a rent. Come back on the street and talk with salesman. Choose the second option (a call to Marconi) and say you will try to call the landlord (last option). Ask Marconi if he still waits in the hallway (last option).
Go to the flat. Take a box full of junk from the bedroom (next to the door). Leave the building by using the door and go to the salesman. You will get a hammer.
Go to pawn shop and show the box to Mel. Click on each of the items. Finally, Randal sells the ring for a lot of money.
For selling the ring you unlock the achievement 'Cursed'.