Diagnosis
The control board has likely entered a lockout state. This is a common reset condition, often triggered by a brief power interruption.
How to Fix It
Unplug the microwave from the wall outlet for two full minutes. This clears the volatile memory. While unplugged, press the Start button once to discharge any residual power. Plug it back in. The display should reset and be operational.
If That Didn't Work
A failed control board is the next likely cause. Check for any signs of electrical damage on the board. If the reset procedure fails, the control board requires replacement.
Heads Up
This model does not have a dedicated 'Reset' button. The full power cycle is the only user-accessible reset method.