Volume buttons don't work on center uni...

Hi, I'm helping out a friend who is too ill to solve this problem for herself. I purchased a used Lifestyle center to replace her broken one. The problem I'm having with the replacement is that the volume buttons don't work on the unit itself, or with the remote from her old unit. The only way to adjust the volume is from the Acoustimass unit. Is there a solution/reset of some kind or did I buy another broken one? Mary