Problem with V Ampire LX 1200 H

Hello I am new in the comunity.

I have a problem to conect the L and R outputs to the Berhinguer Ultrastack 4x12, threre is no sound, few days after my little son conected booth outputs with one jack wire, and I turned on because I don't know that he was conected that cable, the fuse was braked, I changed it for one new, and all works correctly but the L and R outputs doesn't work.

If somebody knows what could happend ? Thanks regards.