LOL, you have a strange history of having amplifiers mysteriously blow up without you doing anything to it while it's "not hooked up".
That should tell you something...
You bought an amp. It worked. Transaction complete. next you remove the amplifier and store it for a month, then re-hook it up. Now the amplifier doesn't work. These are not related; these are two different actions. For example, i bought a deck here on the forums. it worked fine when i received it. TRANSACTION COMPLETE. A month later it stopped reading CD's. This was not the fault of the original seller; it worked as described when i purchased it. You are essentially asking for this seller to provide you with a warranty on your used goods. If you need a warranty and are willing to to pay for a warranty, don't buy something used on a forum. If you want something with a warranty, buy it new and fry it to your hearts content, then use the warranty you purchased to have it replaced.