Go to Vehicle page and make sure you have all motors (NW, NE, SE, SW) mapped to an output. Then go to Output page and make sure that it looks reasonable; motors that work are configured like motors that don't work. Make sure the banks are configured correctly, or just set them all to whatever works. Understand that e.g. bank #1 may actually affect outputs 1 and 2...
Finally, if your board is broken, you can move some motors from outputs that don't work to outputs that do work (Vehicle page then Output page), like move from outputs 3 and 4 to outputs 5 and 6.