Problem with 'stuck on lock' and system shutdown

Hi, and hoping someone out there can help me. My Fuse has recently started displaying the ‘lcok’ symbol’ which I’ve been unable to get rid of.  WhenI have somehow managed to turn the device off, wehen I try turning it back on it diplays the following:

Please unlock the HOLD switch to power on. System shutdown. 

Occasionally I’ve manaed to to get it going again but it is getting worse now and mostly will only power on and play if I plug in the USB cable.

I’ve tried reinstalling / updating the firmware but I’m still getting the problems.

I’ve also tried leaving it on so it drains the battery completely, as I think I’ve seen suggested elsewhere on the forum but after a while it automatically turns itself off.

I really love my Fuse and would be grateful for any ideas to get itback to full working order!