Downhaul doesn't matter in this case: If you are able to get the boat partially up, the water runs of the sail anyway.
I guess it was 25kts plus. The wind pushes so strong under the sail, that it is out of the water (more or less) and the bows turn into the wind. On my boat the mast is than in a horizontal position and doesn't touche the water any more. It is easy to get the boat half up, but than it bears away, the wind catches the tramp and this stops the righting (my boat starts sailing in this condition with me on the wrong side). Once I tried it three or four times without any success, finally I just jumped backward once the boat was half up and that did it. Here is it on video. Wind up 2:00min to see the capsize and attempts to get it up. It took me actually over 7mins to get it up.

Or as Jake said, go backward to turn the boat. Normally it should work if the mast and bows are are pointing 45deg to the wind. Once the boat starts to right move forward quickly.

Cheers,

Klaus