Toys playing by themselves

Although there is more coming in regards to my previous post, here's an update. In the upstairs playroom, there is a kitchen that makes stove and other kitchen sounds when you push the buttons on it. Recently, we've been hearing strange sounds from upstairs. Last night I confirmed it. I stood in the kitchen and waited patiently. I heard what sounded like someone playing with the toys upstairs and snuck quietly up the steps. The kitchen set was happily bubbling away, as if someone were turning the knobs.. the knobs never moved. It kept going off again and again, for no apparent reason. I finally said something out loud, and it stopped. it didn't go off again. I looked at it, took out the sound module, put it back.. everything looked fine. I went back downstairs and damn if it didn't go ff AGAIN! This time I grabbed the screwdriver and took out the batteries. I'll take it apart later and look for any short circuits... so far haven't found a reason for it! What do you think?