I to had a LG refrigerator declared "unfixable" and bought back by LG, but I actually decided they were idiots and fixed it myself after having not only their local repair people fail to fix it, but the "expert" from LG's regional center come out and diagnose it. (It should be noted that he diagnosed the condenser, the only part not already replaced at that point, and that failed to fix it so, they declared it unfixable).

Turns out in my case, the leak was in the yoder loop, a modern trick for increasing the efficiency of a refrigerator by running a high pressure refrigerant line around the doors to avoid needing electric defrost loops (what pretty much every fridge made pre ~2005 or so has).

And since the yoder loop is embedded in the spray foam insulation between the exterior and interior of the fridge is is largely unrepairable because the insulation would have to be destroyed and somehow partially refilled, which wouldn't be possible without adding a bunch of access holes/etc to the exterior.

So, I bypassed it, as a "research project" before buying another fridge, something the LG folks told me wouldn't work, and the tech refused to do. Which funny enough i'm an EPA certified small appliance repair tech (don't ask! lol) so, it apparently is just up my alley. And guess what 5 years later is still going. I've had to manually defrost the ice maker fan once in that timeframe and it does tend to get some condensation build up on the bottom of the french doors, but nothing that wipeing it away every few days doens't solve.

As an additional bit of fun, this refrigerator has a steel condenser and both aluminum as well as copper tubing/fittings.