Try reloading the factory settings:
1) Initialization: Hold "Enter" and "0" while turning it on.
2) Preload: Global mode, top right dropdown menu, "Load Preload/Demo Data"
3) Version Check: Displayed while booting.
To update the OS, go to
www.korg.com
1) Click on Support tab on top of page.
2) Select "M50" from the "Select Product" dropdown menu.
3) Expand the listing under "Operating System" and select
either:
M50 System V 1.1.0 Upgrade 61 Key and 73 Key
or
M50 System Version 1.1.0 Upgrade - 88 Key...depending upon whether you have an 88, 73 or 61. In either case, make sure you select Version 1.1.0
Carefully follow the instructions for updating the OS.
If none of these things work, you will need to contact your local Korg authorized representative.