Will Not Stand Up
The most likely cause of why the Dyson will not stand up is a misalligned valve carriage.
PLEASE NOTE: If your are in anyway unsure of any of the steps listed below. Please consult a qualified electrician and always remove the plug from the socket before commencing work.
1. It is the misallignment of the valve carriage that prevents it from standing upright. As can be seen from the picture below. Because the valve carriage has slid downwards the projection on the cleaner head (red arrow) is above the valve carriage (blue arrow).
2. To fix this depress the black button (red arrow) and then rotate the valve carriage upwards in the direction of the blue arrow. It will now stand up.