Diagnosis
The main control board is failing. Moisture or a power surge can corrupt the touch panel circuitry.
How to Fix It
First, try a hard reset. Unplug the dryer from the wall for 5 full minutes. Plug it back in. This can clear a temporary glitch. If the problem returns, the main control board (part DD97-00857A) needs replacement.
If That Didn't Work
Rarely, the touch panel itself (the membrane) can separate from the main board. But on this model, the entire user interface and main board are usually one assembly.
Heads Up
Before replacing the expensive board, ensure the dryer is on a dedicated circuit. A shared circuit with a fridge or microwave can cause voltage fluctuations that damage the electronics.