Diagnosis
Liquid has seeped under the control panel membrane, causing a short circuit. Common from splashes or washing the lid too close to the base.
How to Fix It
Unplug the blender. Wipe the control panel completely dry. Let it sit unplugged in a warm, dry area for at least 48 hours. This can allow minor moisture to evaporate. Do not use a hair dryer.
If That Didn't Work
The control board is likely damaged. The membrane panel and board are one integrated unit. The entire main control assembly must be replaced. This requires disassembly of the base.
Heads Up
Never submerge the motor base or run water directly over it. Clean only with a damp cloth. If phantom button presses persist, unplug it. A faulty control board is a fire risk.