Hi Anand,
I fear that this is a hardware defect (Key Matrix or Key Scanner IC is probably defective).
Please make sure to back up all user data that is stored in the User drive. The easiest way to do this is in USB Storage Mode (connect the USB-to-Host terminal to the computer via a USB-AB cable, wait briefly until the Genos User drive is displayed on the computer as an external drive, then select all data on that drive (e.g. with Ctrl+A) and copy it to a new folder on the computer.
Alternatively, you could copy the files to a USB stick. Then you have to copy each file type (e.g. styles, registration files, multi pad files, MIDI files, audio files etc.) separately in the respective file selection display.
I also recommend to save a .bup backup file (using the internal Backup function) to a USB stick. This backup then contains the content of the User drive and also all user-defined System settings.
It is also ideal to save the so-called setup files separately. You do all of this in the display "Menu > Utility > Factory Reset/Backup> page 2/2".
Incidentally, the Expansion Wave Memory can NOT be saved. Here the content of the YEM or the .cpf/.ppf Pack files is the backup.
As already suggested, you could try to reload the current Firmware (version 2.02) on the Genos. To do this, you have to copy the unzipped file "GENOSSETUP.PRG" into the root directory of a USB stick, connect the stick to the Genos and then switch on Genos while holding down the STYLE START / STOP button.
Incidentally, reloading the Firmware does NOT delete the content of the User drive. Only the user-defined System settings are reset in some cases.
If this does not help, there is a special shortcut for the Genos to carry out a complete Factory Reset (including resetting the internal User drive and the System Boot parameters) WITHOUT having to start the internal Test Program. Note: Yamaha does not want this shortcut to be posted publicly on the internet. You are welcome to contact me via PM (Personal Message) in this regard.
I can give you also all needed information how to use the internal Test program (to check, among other things, all internal RAM and ROM memory chips).
P.S.
Unfortunately, I estimate the chances that your problem can be solved "by software" (Factory Reset / reload current Firmware) as relatively low. Nevertheless, I would try as described (unless you have a Yamaha service center nearby that can take a look at the device).
Best regards,
Chris