A modular light emitting diode (LED) display sub-assembly includes a frame and a plurality of LED display panels. The plurality of LED display panels are attached to the frame. Each of the plurality of LED display panels includes a housing, a printed circuit board attached to the housing, and a plurality of LEDs. The housing includes plastic sidewalls and an outer surface of the modular LED display sub-assembly. The plurality of LEDs are attached to a front side of the printed circuit board. The modular LED sub-assembly further includes a data receiver box mounted directly to the frame. The data receiver box includes a power management unit and a signal processing unit. Each of the LED display panels and the data receiver box are sealed to be waterproof and are configured to be exposed to an external environment without a protective cabinet.