Down on hands and knees installing flooring. Left hand/ wrist are swollen, pinky finger and palm numb, hand weak, can't open hand completely.

Compression of nerve. which will hopefully be temporary. The usual position for a person installing flooring is to support your weight on your extended wrists. This compresses/stretches the nerves as they travel in your wrist to your hand. What you describe is serious, though. But if you stop injuring it, it should improve in a few hours...up to a day or so. Splint it. If it persists longer than 12-24 hours, go to ER.