So it's stress causing it. They do get very stressed by environment changes. He's trying to escape because his territory smells different and it's scared him. I just remembered when I had this phase with Charlie I set up the playpen around his cage and left his cage door open in the evenings and he would come in and out of his cage - so then no need to chew the bars because he wasn't in the cage unless he wanted to be. It does mean you need to be there to supervise though, as they can escape from playpens. And yes he did then try and chew out of the playpen, so I had to keep blocking off certain corners that could be chewed. There was no way he could get over the top as it's 2 foot high correx lol. But he did have a good go by climbing on top of his cage and trying to run up the flying saucer.
It took a couple of weeks for him to settle down. So I know that means a fair bit of attention in the evenings for the next couple of weeks. I would keep out of cage time to evenings only as he should be sleeping during the day really and will get more stressed if he doesn't get enough sleep.
The other thing that helped was taking him to a different room for some out of cage time - it distracted him from the 'presence' of his cage and the changes. So sometimes I'd set a smaller playpen (cardboard castle thing) up in the bedroom or let him have the bathtub for a playpen. Time consuming but it shouldn't need to be for too long. He was much happier out of the cage in a different room. And also was more relaxed when he could walk in and out of the cage into the playpen round his cage. he was usually voluntarily back in his cage by bed-time and I'd shut the door. He'd start bar chewing before we went to bed and that's when I'd turn the lights out and we'd leave the room and go to bed. If I came down for a peek later he had stopped - he only did it when we were there.
he just needs to get his confidence back and stop feeling scared. I know how frustrating it is and it makes you start feeling annoyed with them, and maybe they are trying to annoy you out of revenge lol. But just try and be patient with him and find something that works to help settle him again. So ignore my suggestion about changing anything in the cage as that isn't appropriate now.
I would suggest, setting his playpen up round his cage if you can - say between 8pm and you going to bed. Checking to see if he's trying to chew out anywhere and blocking off those areas (a book or a toy eg). hide bits of food and treats in the playpen (food is a big distraction!). Have a wheel or flying saucer in the playpen so he can burn off his energy (but don't take the one out of his cage!)
If it's not possible to set up the playpen round the cage, then get him out around 8pm and let him play in the bathtub for at least an hour, then pop him back and meanwhile have cardboard woven round the areas he has been chewing. (I remember Charlie looking quite surprised to find something blocking his bars - but then he just moved along a bit to another area). I think I gave him some calming herbs as well - chamomile chew stick in the cage. He should eat it because it also has sunflower seeds in
Rosewood Boredom Breaker Natural Treat Sunflower and Chamomile Sticks: Amazon.co.uk: Pet Supplies
So
1) Weave some bits of cardboard round some of the bars - just torn up toilet tolls or cereal packet or whatever.
2) Get him in a routine of being taken out of the cage at a set time each evening - say 7 or 8pm and have an hour in the bathtub or playpen. If you can set the playpen up round the cage leave it up all the time, check for gaps before opening his cage door and open his cage door around 6pm each evening. There's a psychological process there - he knows he can get out at that time every day. And let him pop in and out of the cage like that so he starts to feel more in control.
3) Talk gently to him through the bars - he'll react to your tone of voice - if you start sounding cross and frustrated it will become a bigger battle of wills! Say sorry lol - I'm sure Charlie understood when I said that. I know that sounds naff but I sounded so apologetic when I said it that I swear he listened. I just said sorry for all the changes but everything was back to normal now.
4) Give him a chamomile treat stick in his cage, or if you have some chamomile herbs (not tea it's too bitty) scatter a little tiny bit in the cage - they can eat the flowers. Treat stick is easier.
One last thought (remembering the lingering smell thing with Charlie's cage when it still had the scent of the other place he'd been) - is if it was the smell of the cleaning stuff that is bothering him it might still be lingering. But I'm sure you didn't clean it any differently to the way you normally do. The scents of cleaning stuff can be too strong for them. But if you didn't do anything different it probably isn't that and more likely to be the combination of the cage clean and moving him to a different position as Piebald said.
I had a lot of problems with cage cleaning when we first had Charlie as he was neurotic at first and very nervy and jumpy for a long time. I had all sorts of useful tips on here, and found a combination of things helped. Firstly, spot cleaning and emptying his potty I'd do when he was still in the cage, and talk to him while doing it. He still didn't like it but seemed less stressed than when he'd been out of the cage and came back to find it had changed. Secondly I took the tips from Erin's Hamster's cage cleaning video and it really worked well. (Linked below), so now I rarely do 'full' cage cleans. When I do do a 'full' cage clean it's actually only a partial one, and do the substrate one week and the toys a different week, and only ever replace half of the substrate. But that's only about every 3 months, and just do spot cleaning in between. If he uses a potty that's even easier as you just empty the potty every four or five days and the substrate stays mostly dry - unless he pees everywhere lol, then just take out a handful of wet substrate and replace it with a handful of dry and mix it in so it still smells familiar. Check out the video though - it really helps and has some good tips
It all sounds a bit pernickety, but you just have to imagine if you came home one day and found someone had moved all your furniture around and re-decorated it wouldn't feel like your home and you'd feel invaded. Especially if they'd changed your duvet covers and you didn't recognise them lol. They are just very territorial about their cage environment and like things just so. OCD. Sorry you probably know a lot of that anyway, so apologies if I'm going on a bit ha ha.
Here's Erin's video
https://www.youtube.com/watch?v=5jVnEjrXbww
Soon you two will have a lovely bond and he will regain his confidence and trust and he will be a little friend
I've also added a couple of my videos from the time when Charlie was having his mad time - they're interesting now, but it wasn't pleasant at the time and I found it quite upsetting that he was running round and round like a mad thing. The other one is how to make the playpen. Not sure how escape proof yours is. This one is fairly escape proof but it needs bulldog clips top and bottom or they can pull the corners apart, and still needs a bit of monitoring (ie being in the room and checking the joins and blocking off any tiny gaps when it's been put up). When Charlie was in this phase I found it easier to leave it up permanently and just removed the front piece if I needed to get in to his cage.
You can see how cross he looks in this one - just to stress him even more, after the change of environment, I had to take his wheel out because he got trapped behind it while he was running madly round and round and that just made him worse. I've turned it into an 'amusing' video but it certainly wasn't funny at the time. Once I'd put the wheel back he went frantic for wanting the flying saucer substitute back. Nightmare. But it all settled down in a couple of weeks. You can see him starting to chew at the bars on this one, just before I let him out to his wheel.
https://www.youtube.com/watch?v=7icHDD-9KRY
This was after I put the wheel back (safely attached upside down now) and he went frantic wanting the flying saucer back. He started climbing up the cage to try and get out. You can see him going in and out of the cage and the playpen here, which is a lot better than bar chewing. Although he tried to use the flying saucer to run up to get out of the playpen, it also distracted him and he started just running on it for fun.
https://www.youtube.com/watch?v=sIPOOsN-YW0
This is him now - docile
https://www.youtube.com/watch?v=Bb6mfqa4ZPM
And this is how I made the playpen (with tips from others on here!)
https://www.youtube.com/watch?v=AvXJ-Jbo0CM
The downside to the playpen is the cost - the sheets of Correx/Coroplast cost about £20 altogether, but you could use cardboard if you can get hold of any large cardboard boxes.
Re: Impossible Syrian
As for Erin's video, it is my gospel lol. When I clean I keep at least a bin full to scatter above the new stuff. I didn't use any chemicals apart from warm water. I left his nest for a week as well as his toys as I always do. I did not change toy position but I did add in a higher level now that he is older. But last night was his fist night not monkey barring as far as I know 
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