Nommo Pro wierd behaviour

Since i got my Nommo Pro speakers after some time they were turning off. It wouldnt be wiered if i could normally turn them on. I have to disconnect a specific cable (probably power one) but don't really know wich one and wait a bit. Then it starts working. They turn off after i think random ammount of time. Sometimes they last for a couple days and sometimes a few weeks. If someone knows the sollution i'd love to see it.