Problems with my acoustic bass

Ok here goes guys. I have a washburn AB-34 acoustic bass. When I play first i have to pop in the thing that holds the battery and has the eq ad volume on (not sure what it is called). And it works fine thn a couple of minutes later it will cut out and stop working i already tried to change the battery and it still does this. I really need to get this solved as my band is going to be playing some shows coming up where i am going to need to use my acoustic. Any help would be greatly appreciated.

 

well i am not sure.. i dont know exactly how to pul the electronics out of my acoustic bass

 

Well the problem there lies in the fact that I bought it used

 

well i just pulled the electronics oout of it and looked all the plus were in all the way so i put them back in and didnt tighten the screws as tight as they were and it appears to be all better