problems with instinct speakers output

today i received a package with the hercules dj control instinct controller. and it does not work as it should. speaker output defective. the sound was going to l & r channels only if i hold the cable by hand. and if i use the speaker output + rca output and does not hold speakers cable by hand then stops working and one of the rca channels too. i used all the cables (and 3.5 headphones) in the house - nothing works! please help! see the my small videos:

what do i do? send it back to the store? i wanted to take it to replace an my old mp3 e2 controller, but now i doubt that i have to buy - new instinct, air or mk4? thx