DIAGNOSIS The blender is detecting an issue with the motor load or the connection between the cup and the blade base, triggering its safety cut-off. The flashing lights are the error indicator.
FIX First, unplug it. The most common fix is to unscrew the blade assembly from the cup and check for debris—a piece of fruit or ice jamming the blades will cause this. Clean it thoroughly. Then, make sure the cup is screwed onto the blade base *tightly* before you twist it onto the motor base. A loose connection here is a huge culprit.
IF THAT DIDN'T WORK The motor base might be overheating. If you've been trying to blend something very thick or frozen, or ran multiple cycles back-to-back, let it cool down completely (like 30 minutes) and try a simpler, softer ingredient.
HEADS UP These personal blenders aren't built for crushing ice or super-frozen fruit straight from the freezer. If you do, you have to use liquid and pulse it, not hold the button down. Otherwise, you'll trip this error constantly.