The KS is showing Packet Error on the screen to indicate that it has received a packet error during the data transmission. If this happens, the OS will not be uploaded into the KS flash memory. Switch off and try again. If this happens repeatedly try using a SysEx utility to send the OS to the synth.
Sysex Librarian for Mac (www.snoize.com) and MIDI-OX for PC (www.midiox.com) are both free to download from the web and will reliably send data to the synth. The latest OS is available in SysEx format from the 'downloads' section of our website.
When using Sysex Librarian ensure the synth is connected and ready to receive the OS before starting the program. In the program, select the relevant MIDI output from the drop-down 'destination' menu and then click on 'Add...' and select the OS file you wish to load into the synth. To send the data click 'play'.
When using MIDI-OX make sure the synth is connected and ready to receive the OS before starting the program. In MIDI-OX select 'Sysex...' from the 'view' menu to open the SysEx scratchpad window. In the SysEx scratchpad window select 'load file...' from the 'command window' menu and select the OS file you wish to load into the synth. To send the data select 'send SysEx file...' from the 'file' menu. In MIDI-OX you can increase the SysEx buffer size by selecting 'configure buffers...' from the 'options' menu. If you continue to get packet errors when using MIDI-OX then double the buffer size until the OS update completes successfully.