I cannot pairing air unit to GCS

I relized that there are aonother same topic like this but I did almost every instruction on there topic but I still cannot resolve it yet.
I did not update any firmware because of my herelink is old one that doesn’t has activation key.
I use BEC for supporting air unit with 9v separate from the other unit.
I did reset my GCS as well but still cannot resolve it.
I did flash air unit too.

Pls help me

Please try to update your firmware to latest. Reflashing usually solve the pairing problem in old units.
If you don’t have the key, contact your reseller to get one.

I bougth it from a small reseller that doesn’t exist anymore and i cannot contact them too. But i still have the box that have serial number. can the main company of CubePilot sent the activation key for me?

Is there any develop company’s policy for helping us like in my case ?

Now, I found the old version of air unit firmware (AU01200226) on the internet that still downloadable. I could flash successful by manual flash via cmd (fastboot>>flash_all.bat) and could not use flasher.exe yet as shown in the pic. Then the LED2 back to lit but still cannot pair with controller. So, please give me the latest air unit firmware set as the old version (Pic 2).