Are you using cpuminer or cgminer? There's a specific set of bytes you have to send to the controller that tells it to disable the BTC units. cpuminer does this, and that's what the controller is using afaik, whereas cgminer doesn't.
I've noticed that even when just scrypt mining the controller board runs cgminer with the following parameters(run a ps command while scrypt mining)....
/www/soft/cgminer --dif --gridseed-options=baud=115200,freq=850,chips=5,modules=1,usefifo=0,btc=0 --hotplug=0 -o stratum+tcp://[your.pool.com] -u [your.username] -p [your.password]
so there is a possibility that one of these statements causes the cores to shutdown and draw no power
That must be using a custom version of cgminer then, as the sources gridseed published on github don't support those flags.
EDIT: I retract that, they posted updated cpuminer and cgminer sources less than a day ago that support those flags.