Did I blow my tube amp?

Did you check the B+ fuse?

When I changed the power tubes in my older VTL/Manley designed tube amps, I had the whole system connected and I changed one tube at a time, turning the amp off each time I replaced a tube and turning the amp on to bias the new tube. I also made sure after changing each tube that the other tubes were biased correctly, as changing one affected the bias on the others.

I am no expert in the matter but my Cary amps are biased with all connections removed as recommended by the manufacturer. Best would be to check with manuf. Or trouble shoot with the user manual.

It is my understanding that you never under any circumstances
power up a tube amp without connecting to your loud speakers.
Yes there is a very good chance you have damaged your amp.

Thanks guys for the inputs so far. I must add that the amp I have is not a Manley, I'm just following the steps in the youtube video, which had a Manley Stingray in it (I think it was EveAnna Manley from Manley Labs that did the biasing).

I know that some manufacturers recommend having speakers connected at all times before turning on an amp, but I also know that for Cary amps it don't matter. In my case though, the owner before me had it on once without speakers connected, and it was fine after he passed it on to me.

I checked all connections several times, even swapped in a solid state amp and music played normally at the speakers. I even had experience turning on a Yaqin tube amp before without speakers connected and it was fine after. In my case, there was no input signal connected at the time of the biasing, so there should be no load and the output transformer should be at idle.

The amp still turns on and all tubes lit normally, just no output at the speakers. The tubes usually get really hot when playing, but they seem to be just idling without getting hot. Would a dead fuse cause this?

Purposely withholding the name and model of the amp will not get you any meaningful info.