If all four LEDs stay on solidly and you never get to the point where a single LED is on, it may be that there has been an update error, or you have accidentally entered ‘update mode’.
When starting the update process, the firmware on the synth is erased, ready to put the new firmware on. If the update is not completed successfully, the result will be that you only ever see 4 LEDs lit solidly.
Don’t worry, it’s still possible to put the firmware back on the device, just contact support@ modalelectronics.com for help.