I have a veil chameleon that is very weak. I don’t think he has MBD. I’ve been syringing water into his mouth and keeping him in towels that have heating pad under.
You will want to remove the heat pad. These can overheat them. Be extremely careful syringing water into his mouth. Their airway is at the very front of the mouth under the tongue and you can very easily aspirate them. This will show you where it is. http://www.muchadoaboutchameleons.com/2014/05/how-to-give-different-medicines.html
He looks to be in a full decline. I do not think he will make it until the morning.