There is a screwdriver under the drawer. Press it to obtain this item. Next pick the pliers hidden in the potted plant. Use the screwdriver to open the circuit board and then select pliers for the wires. A puzzle will appear. Notice that the four symbols here represent the mathmatical symbols of Multiplication, Addition, Division and Subtraction. There are also 2 types of shapes in each symbol.
To solve this puzzle you need to do the math considering the sides of the shapes in each symbol. So:
Circle (0) times Square (4) = 0
Triangle (3) plus Pentagon (5) = 8
Triangle (3) divided by Triangle (3) = 1
Pentagon (5) minus Triangle (3) = 2
So change the numbers to 0812. A glowing light will appear. Grab the key from here and escape.