To answer the question at #17 (above)... I found the following info for my Casio LK 42. Maybe this will help:

Automatic shut off and power on alert.
•
To defeat hold down the *TONE* button on power up. That will disable these functions. When these functions are turned off, the keyboard does not turn off automatically
and no automatic light up key alert is performed no matter how long it is left with no operation being
performed.
•
Auto Power Off and power on alert are enabled again when you manually turn off
power and then turn it back on again.