There are too many possibilities and overheating does have some symptoms you would have seen, gapping, sticking to the bottom areas, pacing to get out and away from the heat. Your ambient was right in range and the lower cage should have been ok. I would suspect an underlying infection, organ failure or heavy parasite load as these are the most common things that show little outward signs but can be fatal. Chameleons are low on the food chain and try to hide their vulnerabilities for survival's sake.
One other possibility is poisoning from the new food source. Do you know what the black crickets were fed or how they were kept? They were the most recent change. If they ate moldy food that could cause problems.
One other possibility is poisoning from the new food source. Do you know what the black crickets were fed or how they were kept? They were the most recent change. If they ate moldy food that could cause problems.
... he did look a bit dehydrated though just from how his eyes were sunken in. I’m sorry.
