We know nothing about a Webasto ... 2010. The engine coolant pumps up to it, but it doesn't pass the Webasto unit into the heater lines. Pull the knob on and it starts up, feels like the pump is moving, still no water moving,
Unless the pump impeller is frozen or the boiler itself is clogged, there is nothing about this setup that should keep coolant pumped from somewhere else, such as the engine pump, from flowing. I would look for another shutoff valve somewhere in the line that is in the closed position. We have two such valves in our system, and with either closed, this would be the symptom.
and it doesn't light up and after a minute the light on the knob goes out and it does a shut down. We think there is something real simple going on here. We just don't know what.
There are as many ways to plumb and wire a Webasto as there are posters on this board. So without a diagram of how your unit has been wired it is almost impossible to diagnose the problem remotely like this. Also, these units must be serviced periodically, even if they are never run. In fact, NOT running them is a sure way to get them to fail So you really want to take the whole thing apart and check the flame chamber, the nozzle, the flame sensor, and both thermostats. Instructions are in the DBW-2010 manual, available in PDF form in many places on the 'net.
You most certainly do not want the burner to light if the coolant is not flowing first. So you need to correct the coolant flow issue before you move on to diagnosing the failure to ignite.
When you try to start the unit do you hear the blower start?
If you can find the fuse that powers the Wabasto , turn the unit on and before it shuts itself down pull out the fuse. This will reset the controller and erase all the codes. Put the fuse back in and try starting again.
Umm, there are no "codes" stored in a DBW-2010. The little control box contains nothing but electromechanical relays and a handful of discreet semiconductors. No other "electronics" at all, and certainly no code memory.
Moreover, it is highly
inadvisable to interrupt main power to the unit at any time in the cycle. Killing the blower before the cool-down cycle finishes will almost certainly blow the thermal protector, and might do much more serious damage.