Great amp, crashed and burned after 30 hours... Buyer protection?

When buying used over the internet there are no fail safe ways to guarantee that you won't ever get scammed.  The risk comes with the territory.  Use caution and common sense.

Did your buddy happen to deal with a Audiogon member or someone from another site?

It may be off-base to blame the seller 
given the sudden and catastrophic failure of the gear, it may be a crap build equipment issue.

i had three (3) sudden .... And mean unforcasted and SUDDEN .... Catastrophic failures on the $4k top-of-line AVR and blu-Ray player.
with the receiver , it was fine and next use two days later .... Kaboom! New motherboard replacement and gone for 5 weeks 
warranty coverage ... Okay....but. Something amiss. 11months later was an instant repeat. Good thing it had a three yr warranty 

the Bluray player ( a $1500 unit) crapped out catastrophically suddenly in mid-movie . It was 27 months old and three months out warranty so I was SOL with repair costs exceeding its FMV.

I sold the AVR and replaced the BR with a quality build Euro unit...and Euro / USA quality build separates 

the moral of the tale:

- the  expensive and shown-to-be-unreliable Chi-fi gear I had was crap build POS gear ...full stop

- mfg OEM warranty through a distributor matters. Too many have only a 1 year .... Caveat emptor. Most used gear won't have it and the bargain price reflects that.

- your seller may have sold used gear on a proper belief that it was out-of-warranty but all good ON DELIVERY with no knowledge of any issues. The risk is entirely yours 

I think I read that oldstyles buddy's techie found "counterfeit" parts, which led directly to the failure, therefor whomever repaired the first time is the culprit. Also it was the sellers attitude that set him (her) off. The techie said it was lucky it lasted the 30 hours, which smells of deception on the sellers part, why else would he lay down "attitude"?

I suppose the "recourse" is to buy new with warranty from a reputable dealer.