Some older HECUs were recalled. Do you know for sure if your car was part of, or serviced for, the recall? Here's the recall on the HECU/brake fluid:
2011 HYUNDAI GENESIS 4 DR RWD which covers cars made up until March 28, 2012.
When the HECU failed in my 2009 4.6, it was before the recall and was replaced under the original factory 5/60 warranty. By the time the recall was announced the original HECU would have been recalled, but I already had the new design installed.
When the HECU failed in my 2012 4.6 last year, my car was not listed as part of the recall so it was not covered, but I have an extended HPP warranty (Platinum 10/120,000) that covered replacement at no charge.
Hyundai's 2013 response to NHTSA detailing their action plan for executing the recall:
https://static.nhtsa.gov/odi/rcl/2013/RCDNN-13V489-9416.pdf
which states cars made before June 1, 2010 will all have HECU's replaced, after that they would replace brake fluid and inspect the HECU but would not automatically replace HECUs sight unseen. Their rationale is that at the time of the 2013 letter, the likelihood that the HECUs were damaged is dependent on "time in service with the corrosive brake fluid."
Call me cynical or conservative but my take on this is: Since Hyundai stated the longer you have corrosive brake fluid in the car, the higher the probability the original design HECU will fail. And since all brake fluid is hygroscopic, eventually all brake fluid becomes corrosive. So every single one of the original design HECU units in every 1st gen Genesis will eventually fail. Hyundai is a business and like all businesses they aim to maximize profits for their stakeholders. They were able to get NHTSA to agree to their limited recall, which did not comprehensively replace all HECUs in all cars with the newer corrosion resistant actuator valves. And even some of the newer designs that weren't part of the scope of recall still can fail (as with my 2012). So their fix isn't perfect either.
Bottom line: every single 1st gen Genesis sedan on the road that has an early design HECU is a rolling time bomb at risk of complete brake failure. Sooner or later, they will all fail. Protect yourselves, people.
Swapping in someone else's used unit or a Copart unit may be fine. But you will have no way to know if the unit is the newer design unless you can figure out by part number which units are pre-recall and which are post-recall. A smart service writer or parts counter clerk at a dealer can probably look it up for you.
Recommend you file a complaint on NHTSA. The more they know the more they can help protect our fellow Genesis owners.