sounds like you've done a lot for this little guy. Very frustrating!
How about taking him out and warming him with your body heat for a while? Like, tuck him under your jacket or sweatshirt. Or go watch some tv with him on your lap under a blanket. Once he's warmed up, maybe he'll sit and bask...
Hi, you gave lots of great info. If you can post a pic of your set up and your chameleon too, that would help us help you.
First, are you sure he's a male? Does he have the little heel spurs?
The reason I ask, is because if you have a female, she might be looking to lay eggs.
Definitely want...
try a hotter basking temp?
Just wondering if the temperature in his new room is different than his former home. If your basement is cooler, maybe his basking spot isn't hot enough. 87 is hot, but not as hot as it could be.
Maybe something in the 90s would make him feel better.
Best wishes!!