Sansa Clip blocked

When trying to connect my Sansa Clip 8Gb to my MacBook, it got blocked. Tried several times to power off (it works after a few seconds) and power on (it starts, show two times “sansa” then the logo and stays frozen showing the logo on the screen.

How can I reset my device ?

Hold the power button down for 20-30 seconds. Yes, it will shut off before this time, but continuing to hold it down for longer will reset the device.

Next, go to Settings > System Settings > USB Mode and set it to MSC mode to use the player with your Mac.

Did like suggested, after charging the device all night. Did hold the Power off button several times for more than 60 seconds. Nothing changes. Is it possible that the device is locked for another reason?

Try this.

Still not working. One additional info : the problem appeared when the device was connected to the Mac while holding the Volume down button pressed. Could this be a cause of blocking?