What's your humidity at? If he dried out like that your humidity is too low. Can you run a hot shower and get the bathroom all steamy, take him in, and rub some coconut oil on the membrane so you can see through it. If you see any veins, just wait. Give him a few more hours. What I would do is make a hole intge air cell, and chip away almost all of the air cell. Don't go below the air cell line. Then rub some coconut oil on that membrane and look for veins. Don't get oil on his bill. Look for him to make any yawning/chewing motions, indicating there's still yolk being absorbed. If he makes them, just put him back he needs more time. If there are no yawning motions and no blood veins, take a pic and post it and we'll go from there. He's been pipped for quite a while, so he probably needs some help.
That's great! The stringy stuff would be the embryo wastes. It is called by many different names, but that's what it is. It's nothing to worry about. So glad he made it out!
