Diagnosis
The control box is hitting a safety overload. This almost always means the desk frame is binding because it got knocked out of square, usually during a move or an overzealous cable management session.
How to Fix It
Unplug the desk. Get down and check if the two feet are perfectly parallel. Loosen (don't remove) the four big bolts that connect each foot to the crossbar. Square the frame by gently kicking or shifting the feet until they're aligned, then re-tighten those bolts firmly. Plug it back in and try.
If That Didn't Work
The weight load might be mis-calibrated. With nothing on the desk, hold the down arrow until it beeps and starts moving, then immediately let go. It'll reset to its lowest point and recalibrate the load sensing.
Heads Up
If you hear a grinding noise during the reset, stop immediately. That means a motor cable is pinched or damaged, and forcing it can wreck the motor.