Create Routing Channel in Jig

What happens here

Once the two holes are drilled in the shelf blank, remove the jig board. Secure this jig board (which now has the two precisely drilled holes) to another, even thinner piece of wood or directly to your workbench using screws to create a stable routing platform. Take a compact router fitted with a straight bit. Carefully rout a channel on the *underside* of the jig board, connecting the two drilled holes. This channel should be precisely sized to accommodate the flat, serrated backplate of the floating shelf bracket, ensuring it will sit flush when installed. Clean any wood dust from the newly routed channel using a shop vacuum.

Goal: Modify the jig board by routing a channel that connects the drilled holes, matching the dimensions of the floating shelf bracket's backplate.