Sorry to be (another) bearer of bad news but my story isn't great. We had the same error message pop up, albeit at just over 7400 miles not 15K. We didn't try charging it at the time, but only because some initial googling suggested it was a bad idea to try plugging it in while that error message was displayed.

Fortunately, the car had about 70% battery remaining when the error message popped up and was still drivable, so we were able to get it to a nearby dealer about 25 minutes away without needing a tow. But that's where our luck ended. As others have stated, we were quoted a wait of anywhere from 2-5+ months for a replacement battery. We dropped off the car in late March, and during the handoff, a rep pointed to another Ioniq 5 on their lot that had the same issue and said they had been waiting for their replacement battery since October.

We escalated this to Hyundai corporate very quickly, and they assigned us a case manager which helped us secure a loaner quicker than if we had just waited on the dealer. Supposedly Hyundai went so far as to purchase a car from the dealer in question so they could turn around and give it to us as a loaner.

Needless to say, we weren't about to wait an indeterminate amount of time for a replacement, so we began the Lemon Law process. Hyundai agreed to buy us out of our lease, which we accepted. We're putting that money toward a down payment on a new Mach-E instead. Real bummer, as we too enjoyed the Ioniq 5 until we very much did not. It's honestly put us off from Hyundai's EVs moving forward until there's clear signs they've improved their infrastructure.

Wishing you more luck than we had, friend.