You will need to purchase the 'Organizer: Toolboxes' under the devices tab. After you have this and store items that run on electricity stuff will eventually break down. This is symbolized as items with a red cog over them. Pick up the toolbox and go the broken down item. Hold down left click on the red cog item on the broken down device and it will fix it.
This achievement will unlock after you close your store for the night after you have repaired your first device.