A chick chair is a good idea.
Can you feel of the left leg joint to see if the tendon is slipped?
Hopefully this baby will come around, but ime, I've found that if they don't get up and moving at hatch and remain unable to stand, move about eat/drink well, they don't make it.
Do you have photos of them or a video of their actions?
For video, upload to youtube and provide a link.
Hard to know if it's Encephalomalacia (Crazy Chick Disease) or not. Some sources say symptoms don't show up until chicks are a bit older (day 10 and up) but I suppose it's possible for...