Have you already checked out this article for further troubleshooting steps regarding the Box Edit install loop?
If you're still having trouble, this would be something our Box Support team would like to investigate with you and will require specific account information. If so, you should contact Box Support to help you directly.
Which browsers have you tried running Box Tools on? If it's not detecting, then we should start looking at the logs to see what is being reported. You can try posting them here or submitting them to Box support.