Buzz the rooftops of Manhattan to see Agent 13 in a lizard costume (technically a Lizard costume), calling for your help from the Kronos building.
Follow the powerline leading from the broken elevator.
It runs behind a giant sign. You can't reach the power source directly, but you can use a Thor to power it up from a distance.
This opens the elevator. Use the pieces inside to build a Groot trackball platform.
Use Groot to unlock the second elevator, revealing the brick.