Hidden <update> mode in PSR-i500/PSR-E463(Maybe other PSR-E Series). Found it!!

[Mysteriouslog6]

There is an update menu , turn off the keyboard , press the START/STOP button and simultaneously press the power button and VOILA!

It would be even better if there was an update file somewhere and it had no verification system.

The way to enter the update menu is similar to that of other Yamaha Keybaords.