It uses non-volatile memory so no battery.
What exactly is not saving? This makes a difference to the solution.
If Midi and other operational settings are not saving...does he realise he must make a "Power On Setup"?
If the problems are related to Flash memory issues then he should download the latest operating system from www.ketron.it
The Hard Drive is not required for this series of instruments to operate - its only for storing stuff that you may wish to load like back up patterns, midi files, sampled sounds etc.