Charging a completely flat Surface Pro 3
A very short one - if you've got a Surface Pro 3 (and this may well apply to other Surfaces) and the battery is totally flat, charging it from a Surface Dock may not work.
If you see the light on the plug that connects to the Surface flashing, rather than showing a solid white light, swap to a "normal" charger to get the battery started. Once you've got some charge into the battery that way, you'll be fine to swap back to the Dock.