Due to the specifications of the macOS Big Sur (macOS11) driver, the unit will not turn on until a MIDI application is started and the unit is in use.
Please check if the A-49's POWER lamp lights up or is recognized as a device when you start up "MIDI Studio" in the Audio/MIDI settings or a MIDI application (DAW).
If the A-49 still does not turn on after trying the above, please also check the following points.
- Reinstall the driver for macOS Big Sur (macOS11).
- Connect the A-49 to another USB port.
If the A-49 is connected via a USB hub, remove the hub. - Change the USB cable.