Models Affected: TL7400
The TL7400 (no longer manufactured) featured a touch screen LCD panel and LCD inverter for video power. If the panel was replaced after February 2019, a new touch screen LED panel was installed with a new LED driver for power, and the brightness buttons will work in reverse. There is no fix for this. This problem is resolved in the next generation TL7600 17" All-In-One Quadcore Computer.