Just got a V-4B today. Worked great when I tried it. Worked great when I brought it home. Then I flipped the standby switch on for a second, and at least a couple of the power tubes glowed RED (to an obviously bad extent). Flipped the standby off as soon as I noticed. At this point no more sound would come out of the amp and cab. Turned it off and here I am! Any ideas what this could be? Appreciate any help!