The default position for the DCCV is open so if you lose the supply to it, the valve will be open. Everything you're describing says you still have air in the system. If you can get the back end on some ramps and then top the cooling system up at the expansion tank, refit the cap, run it up to temperature and then switch off, leave it overnight, that should help shift the air.
Check the level the next day before running it and top up if needed. It can take several attempts at this to clear blocked air from the system.