Go to the ice-cream shop. Climb onto the silver tank, over the handles, hop over the stumps, onto the rooftop, and enter across the window. Once inside, free Vinnie from the freezer, by pulling the shopping window element above the door, using the rope.
You will have to rebuild Vinnie. In the freezer, there is one of the boxes - carry it over to the pianist on the right. You will obtain another box by destroying the crate by the counter and turning it into a terminal.
Use the mechanism for the stairs to appear. Walk over to the left, though the main corridor. Walk into the office, after you have removed the stones and destroyed the lock on the door.
Inside, there are two things that you have to do. First, destroy the armchair on the right, next to the flower pot - there, you will find a trail that will lead you to a key. Place it in the bookshelf on the left and open the safe that appears. Use the bricks to build a statue and push it towards the wall.
The second trail is behind the counter, on the left, under the chair. You will receive bricks to build a color gun swapper. Fire red paint at the button on the right and, after the second safe opens, you will obtain bricks to build another statue. Thanks to this, you will open door to the ice-cream factory at the back of the building.
First, go into the corridor and go up. There, use the terminal. You will receive a white crate that you can hide in to avoid ice. Blow up the silver blocks and push the pipe fragment under them towards the wall. Leave and use the valve.
Then, push the block over onto the conveyor belt below. Using the bricks, build a fan, thanks to which you will reach the second one of the valves, by the right wall. Finally, use the mechanism in the center, where you will get over the ladder.