Some users on Mac computers have been receiving the "hardware disconnected" message when connecting their Rane TTM 57SL after updating to Scratch Live 2.4.0 and above.

This is because your Rane TTM 57SL has an older firmware version installed. Download and install Scratch Live 2.3.3 from here >  Scratch Live Downloads Archive

After installing Scratch Live 2.3.3 go to the Setup > Hardware tab and select to "Update Firmware."
The Rane TTM 57SL should now be recognized by Scratch Live 2.4.0 and above.