Diagnosis
The motor continuing to run after removing the cup indicates the Power Base's safety interlock is stuck. On your Magic Bullet, two small plastic activator tabs (or "buttons") inside the rim of the base must be fully depressed by the cup's collar to complete the circuit. Sticky residue from blended ingredients, especially from a leaky cup seal, can jam these tabs down, tricking the base into thinking the cup is still locked on.
How to Fix It
First, immediately unplug the Power Base from the wall for safety. Turn the base upside down. You'll see the two small, usually black, rectangular activator tabs. Using a cloth dampened with warm, soapy water (not dripping wet), firmly press each tab down and then work your finger or the cloth around it to encourage it to pop back up. Repeat this pressing and releasing motion several times while wiping to dissolve and dislodge any dried-on food or syrup. Ensure both tabs move freely and spring back up. Let the base air-dry completely for at least an hour before plugging it back in for a test.
If That Didn't Work
If the tabs are physically broken or still stuck after cleaning, the interlock mechanism is likely faulty. Do not attempt to use the blender. Check for visible cracks in the plastic housing around the tabs. For a 11-Piece Set, the issue is isolated to the Power Base unit. Your only safe recourse is to contact the manufacturer for warranty support or replacement of the Power Base, as internal electrical repairs are not user-serviceable.
Heads Up
Always ensure the cup's silicone sealing ring is properly seated and undamaged before blending to prevent leaks that cause this problem. Never try to bypass the safety mechanism or operate the base if it runs uncontrollably, as this is a shock and fire hazard.