How to deactivate CS6 from dead computer?

The context:

I have an old CS6 program I am looking to install on a new computer. This would be the third computer I want to install the program on. We can call this computer #3. When I opened the program, I got a message saying that the serial number is already in use by the maximum of 2 computers, and that I need to deactivate another computer to use this program. Well, computer #1 is not one I can access any longer (not sure where it is or if it even functions at all... which I doubt; for all intents and purposes, it is dead and buried). So getting in there to deactivate the program is impossible (unless there are seances for computers). Computer #2 might still have a little life left in it, but it's fast going kaput (hence buying computer #3). For personal reasons, I want to keep the program on computer #2 activated, if possible, for a little bit longer.

The question:

Is there any way to deactivate the program on a machine that no longer functions?

I have so far attempted these potential solutions, with the noted results:

1. Navigated to: Manage my account > Plans and payment (from the menu on the left) > Activated devices. Here it claims I have no devices activated, contrary to the message I get in the program. Nothing I can do here.

2. Navigated to: Manage my account > Account and security (from the menu on the left) > Sign-in and security. Scrolled down to the Active sessions section. Ended all sessions (except current). I still got the message saying to deactivate a computer.

3. Spoken with an actual human via chat support. I had already found the first possible solution listed above. The agent pointed me to the second possible solution. When that failed, the agent had nothing else to offer except to post a question here, or to log out of the program on an old computer. The above context explains why I can't do that with computer #1, and why I might not be able to with computer #2 (or why I don't want to).

Anybody able to help???