IC Failure

Yep you need to open and see the termination. These expensive pieces are often home made and the termination may suffer either lack of skill or equipment quality limitation for home use.

Open/Unscrew the RCA plugs of the malfunctioning interconnect and you'll see where the problem is. The issue itself is in short number of connecting and disconnecting the wires that get eventually stressed and than disconnected.

On my home-made interconnects I used Neutrik lockable RCA plugs. I can abuse these interconnects(pull them by the wire) and be worry free.

WOW DMM MUST read short if there's no damage to IC. If IC isn't operation it should be OPEN circuit i.e. infinite resistance.

If it's a failure in the expencive cable than why they charge so much for home-brew stuff? I'd simply request a full refund and not penny less.
I've compared the termination quality of Siltech interconnect to Mogamy and Mogamy wins 'by unanimous decision' with its built quality: $60/m Mogamy vs. $500/m Siltech. Knowing that termination quality may cary large part in performance, at least 65% of audiophile grade cables are built very poor.
The best built quality among the audiophile grade cables I think is VanDenHul as well as the money spent for performance. VanDenHul also provides a professional cable charts and sufficient per-unit parameters to figure out the best performer for your system.