I am so sorry she bit your son. Yes moving the cage to a different room will stress her and unsettle her. It's best to leave it in one location all the time. If there have been a few changes in the cage recently as well, this may have stressed her and made her more territorial about her environment, so as Socks Mum says, it would be better not to try and pick her up in the cage, but let her walk into a "taxi". These early stages the focus is really on building trust. So it might be better to pick the days. Eg if she is on heat she may well be feeling very active and maverick and not be in the mood for handling. It's not aggression though, it's fear as you say, but possibly also feeling territorial about her environment. I would hold back on the spot cleaning. Poops don't really matter - that may have been her "emergency stash" of poops

They aren't really dirty or smelly, they're like solid little seeds and they actually eat them sometimes, which is normal. They have two stomachs and can redigest vitamins etc from their poops. This is hard wiring, like pouching and hoarding is - in case of food shortage.
So the only unhygienic thing that needs spot cleaning really is the pee. If you know where she is peeing. Most Syrians will use a litter tray for peeing in, if you put it in her current pee location. Although if that is underground that could be tricky. You could try putting it in a corner of the cage near where she's nesting though.
I think for now, it's best to give her time to settle in the new location. If you've moved her back again, then give her time to settle in the original location. It could take a couple of weeks again now. They are very sensitive to any change of environment or location again,
Yes your son must be feeling a bit nervous after being bitten - it always feels personal, but it isn't.
So to build trust, I would give her at least a few days to settle, alone. She maybe wants to escape if she feels stressed by the changes but should settle down into a routine again. Feeding at the same time of the evening helps. Leave any spot cleaning for at least a week.
If she looks interested in coming out, then maybe sort out something suitable as a "taxi". I use a rat tube and have my hands over both ends but they can push quite hard against your hand sometimes, which can make you jump if there's a fear of being bitten and then you could drop the tube. So at this stage it might be better to wear gloves if using a tube as a taxi, unless you have something more enclosed like a hamster ball as Socks Mum mentioned. I would never pick her up from the cage and carry her as she could wriggle free.
It's quite normal for them to chew at the corners or carpet in a playpen - however big a space they have they always want to go further! If you give her the whole room she might be trying to get past the door next!
The idea of the playpen really is to get her familiar with her humans. You can sit in it with her if it's big enough but don't try and handle her just now - she might just walk over you and then she's getting familiar with your or your son's smell and presence and that's the start of building familiarity and trust. It'll only be hands she will try and bite - I doubt she would nip for the sake of it as they don't normally bite unless they're scared or feel threatened.
Anyway you can leave poops for quite a long time without issue - if they start taking over a bit, spot clean some out, but maybe leave a few
The other thing that can make them very anxious is if their hoard is removed so it's best not to remove that.
I hope she settles down in the next few days
