Switch Blofeld off and turn the encoder left to the display rapidly back and forth a couple of times while powering up the unit. Then you should be able to work normally again.
Also, press Shift+Multi,Shift+Multi,Shift+Multi quickly in a row.
Switch your Blofeld on and off 5 times in a row, this works as a reset function.
The use of channel 10 in Multi Mode can cause crashes. Please use other MIDI channels instead and leave channel 10 unused.