I noticed a few cracks on the bottom of my device. I also have an audio issue. My speakers no longer work. I found this post with a really similar issue ( Speaker failure when getting warm ). They seem to be related. I do not recall the cracks being there last week. This is my second laptop with the issue. My original laptop was replaced due to having cracks on the bottom and a bad CPU fan. Also, my warranty runs out today, so hopefully they cover it. I have the new FW 12 Pre-Ordered, Batch 1. It might get cancelled depending on how this goes.
Edit: I have opened a ticket with support.









