The first thing to do is to remove the front frame of the case where the glass is fixed to. To do that, just pull it out of the case.

You will need to remove several layers in order to reach the stock glass.

First level is to remove the metal bracket. Please note that there are two different screw sizes holding it, and it's important to take notice where they were taken from. Using a long screw in the place of a short one, may damage the plastic frame, as it may pierce through the front side.

(Location of the Long Screws)

(Location of the Short Screws)

Next Step is the removal of the plastic frame.

Third Step, is to separate the metal and plastic brackets holding the glass.

We are now ready to start assembling the front grill.

Insert the grill on the metal bracket, as shown in the picture below.

Reproduce the other steps in reverse order to finish the assembly.