Grand Theft Auto San Andreas robbed the militia. This task is really too difficult. Any tips?

This task is called robbing Uncle Sam. You can open the door with the forklift unbreakable switch first, then shovel six boxes together, then break the door switch, let Reid in, enter the forklift and press the keypad 2 and 8 to control the lifting of the forklift plug, which should be much easier.