A modification kit for converting an existing signage mounting structure to an electronic sign generally includes a plurality of display modules; a plurality of sign sections each having a front-facing portion and a rear-facing portion, the front facing portion defining a two dimensional array of bays arranged in a plurality of rows along a vertical direction and a plurality of columns along a horizontal direction, each bay configured to receive one of the display modules, the rear-facing portion for mounting to a surface of the existing signage mounting structure; and a plurality of power routing systems, each power routing system having a power input for coupling to a power source and a plurality of power extensions, each power extension for coupling the power source to one of the plurality of display modules. The modification kit when installed provides the electronic sign.