Parasound JC-1s Not Working

I just bought a pair of used JC-1s on Audiogon. The amps sounded fine until I was shuting down my preamp. My preamp is a tube linestage. While I was turning off the linestage, I heard some funny noise from both amps. Feeling uncomfortable about the noise, I turned the linestage back on. Surprisingly, the left channel amp did not work. The power was on but no signal.

I don't think it was the fuse. I swapped the external fuses between the two monoblocks. But it still did not work.

I wonder if this ever happens to you, JC-1s owners. Is there a switch or something inside the amp to reset? I flipped all the swithces on the back panel hoping that I could get the signal back. Still no use.

I am going to call Parasound on Monday. I know I won't have warranty since this is used. But before I call, do you folks have any suggestions? Thanks.
I just got the amp back and have not had the time to listen to it seriously. But it is working though. The repair cost is under $200. The turn around was quick; it took about several days for them to fix,test, and ship it back.

I am happy with the service and the staff there were generally professional and easy to deal with.

All the fuses were fine. No fuses were blown as I tested them previously. The tech told me the speaker relay was burned. They replaced that and a few transistors.

They kept telling me the importance of turn on and off sequence. Well I am following their recommendations exactly. I just don't understand why I didn't have to do this on-off sequence with my other amps which are BEL Mk V.

I wish Parasound put this on-off sequence recommendation in the owner's manual so that I didn't have to go through the trouble. Thanks to everyone who provided inputs to this matter. Happy listening.
turn on sequence comes down to 1 thing: amps on last, off first. do that, and no worries.