I used a boolean modifier with union to add a hand to body, and after doing that and trying to merge them together in sculpt mode, I got holes in my mesh.. I tried to fix this by selecting all by trait - non manifold and then clicking alt + f. that closed the holes.. but also my faces are now green.. I attached a picture. can someone explain to me how to fix this? and if possible how to smoothen the joined areas.
File : http://www.mediafire.com/file/tl2a1p2mnqavpnd/hand.blend/file
Thank you!