Since these were just shipped, more than likely you simply had a power tube fail rather than the amp itself. During the first week or two after installation is when we encounter the most problems with power tubes.
It the amp simply stopped playing, its likely the fuse by the power cord blew; this fuse can blow if a power tube arcs. Usually its a simple matter to replace the fuse and locate the arcing tube by simply knocking on the tops of the tubes.
the fuses are fine, i was experiencing major crackling in the speaker on one side once switched to full power, damn near blew the very expensive ribbon tweeter on my magnepan 20.1!