I purchased a nice SX-828 last year, all I did was change the old bulbs to led's. Sounded wonderful when I put it up, as good or better than any Sansui & Marantz in that amp range. I went to hook it up today and there was no sound on A, B or C channel. Tried FM and aux, but no sound, all lights function perfect. Any idea what might be wrong? Thanks!!!