GCR Tower in the Bowery district is located north, close to Park Row. You will get the task of hacking this tower as part of your main mission (while attempting to hack a SIM card left by one of Penguin’s goons). Climb up on the roof of the building that has the GCR tower on it and you will have to fight some mobs. Door of the tower is locked and you will notice a small opening in the fence that is unfortunately under high voltage. Equip your remote controlled batarang and shoot it at the opening. Navigate its flight through the electricity and hit the power box on the wall to open the door to the tower. You will be able to hack the tower next with the words “KEEP OUT”. Below are screenshots to better demonstrate what needs to be done.