Responding to PM Request - will crit soon-ish
First off, while you've set up a narrative, you don't give any indication of how you plan to incorporate it. Like, how does the Foundation figure this out? Will it be put in the present or past? These are extremely important questions that you're not really answering.
As for the narrative itself, I should preface this by saying that I'm not too familiar with AWCY?, so I can't comment on any GoI specific logistics. Even so, the narrative just feels very nonsensical? Like, a DJ kills a ton of people at a concert, and their next move is be able to play music to the dead? (Also worth noting that you're not making it clear how the intended effect of the music was. Just for the living? Dead people? Necromancy?) Like, it just feels unintentionally funny and, more importantly, like a plot device to introduce the anomaly.
As for the actual anomaly itself, it's… alright? Like, it's a turntable that just kills people. The "dancing after death" part can make for some good body horror, but you're not really elaborating on that enough.
Ultimately, this is a type of SCP that relies on a narrative to succeed, but what you've given me is both not enough, and also uninteresting. If you really want to make it a thriller, as you've stated, consider where you want to take the narrative and how you plan to incorporate it.