Mistakenly removed the positive battery cable first, now cranks but will not start

Unfortunately, it sounds like this is a security lock out and will require it to be reset and not just an activation. The attached guide goes through how to deactivate it but this needs a reset which is different. Basically it thinks someone was trying to steal it so it needs someone with a tool to tell it everything is okay now.

You don't necessarily need a dealer, just someone who has the OEM scan tool. Many shops around have this tool, you just need to find them. I would suggest spending some time calling around before you have it towed.

Also, did they give you any specific codes when they scanned it? That may help determine if anything else can be done. Thanks

https://www.2carpros.com/articles/how-to-reset-a-security-system