ECM problem, swap solution, ideas anyone?
 

2013 genesis with immobilizer equipped.
The car died while driving. Restarted 10 minutes later but randomly died and had a host of other electrical gremlins like thebcooling fan never shut off until it ran the battery dead. Towed to dealership. They had it for 3 weeks.
They claim it needs a new ECM but stated that it may not resolve the problem.
In an attempt to lower my repair costs, i have been researching online and have found some information. I am hoping somone can confirm if its legit.
Everything i have uncovered basically says that i can't swap the original ECM with a used ECM because this year/model, with an immobilizer, has an ECM that can only be encoded with one VIN number, one time, and its permanent so the used ECM wouldn't ever be able to work. Can anyone confirm this?
I also had a thought of getting a matched set, the main ECM and immobilizer module from a donor vehicle. Can anyone confirm if this will work?
i am trying to avoid the $2000 repair that may not work they say.
Any help would be greatly appreciated.

Can't offer you much but here's my input on your issue. One of my boy's car is a 2005 Chevy Malibu, not even close to u r car but stick with me, which started having electric issues.....door locks off and on, gauges up and down, head lights off and on and most notably the security light illuminated then the engine would die. After much reading and inquiring on the Chevy forums, I deduced the problem was the computer so I bought a used one for 30 bucks and installed it. Much to my delight no lights. However, I noticed the display miles were way off and the security light came back on and the engine stopped again. I figured I bought a bad computer so I bought another for 25 dollars. U guessed it same issue! I found out an older car's computer (2005 Chevy anyway) has memory that cannot be erased and is programmed to that car's VIN number. The only way around this is to buy a new zero data computer for big bucks. Not only do u have to deal with that but the virgin computer has to be programmed by the dealership to your car. After I fell out of my lazy boy I went back to the net and found a place that sells "rebuilt' car computers for around 200 bucks. Even better in your case U might be able to send in your computer and have them re flash the memory. Sometimes....like in my case....they can reprogram the computer to your vin number at their shop that's included in the price! Look under "rebuilt car computers" you will find several sites. I think it's true that you have to start with a non programmed computer but there are ways around this problem. These shops will know exactly what you are talking about and just might be able to help you...and for a whole lot less money! Good luck