Might be worth checking the config file in the .git folder. If the heroku parameters are missing then you´ll get this error heroku param
[remote "heroku"]
url = [email protected]:`[Your heroku app].git
fetch = +refs/heads/*:refs/remotes/heroku/*
the .git folder should be in the local computer file directory for the app you created in heroku. e.g C:\Users\You\Your app.git
Hope this helps