Any idea what melted my car seat?

I have a 2012 acura tsx and I noticed today that my passenger seat appears to have...melted somehow.

If you look at the image it looks like a solvent spilled or perhaps a seat warmer overheated. The only thing that's been on my seat was a new car battery from Costco which sat there for 2 days. I don't see any leaking acid or cracks on the battery though at all and I installed the battery and it works fine. So confused here...don't know if I should pursue remedy from Costco or from my extended warranty for a seat warmer malfunction? This looks expensive right? Replacing the entire seat would need replacing?

Very well could have been residual battery acid. The battery doesnt have to be cracked for acid to come out. This one ie not on Costco, it's on you for being a little careless with the battery.

I have no idea how that could have happened.
Good luck with fixing it ;)

The acid can be neutralized by applying a mixture of baking soda and water and then vacuumed up with a wet/dry vac. But you’re still going to need a new rear seat. A good seat cover should make a decent temp fix.