So before line-by-line critique can help, I believe we need to address some big issues. Let's begin with content. First up is spelling and grammar.
and yet was in prestine condition
Upon testing, it was discovered that when played, SCP-7526 released a high pitch frequency, that can result in hearing loss, and possibly even loss of visio.
Pristine and vision are spelled wrong. And in the second sentence you switch from past tense "it was discovered" to "can result in" instead of "resulted in." These are not the only examples, and I found a lot of spelling mistakes in your article. For these, I recommend putting your draft through a word processor first to catch these. After that, a thorough read-through of your own work should catch any stragglers, as well as words that are spelled correctly, but used improperly. Since word processors aren't pretty good at that, I recommend multiple, out-loud, reads of your work.
Now let's talk about tone.
causing their brain to literally melt on the spot.
In SCP articles, you are ideally trying to imitate the tone of a detached, cold, professional researcher. As such, "literally melting on the spot" sounds completely unprofessional and exaggerated. An example of what clinical tone would sound like is "resulting in the subject's brain matter rapidly dissolving/melting/etc." In order to solve this matter, I recommend reading through other SCP articles(published ones) and also real life scientific reports.
Becoming proficient at grammar and clinical tone is really important here. A single error in either of these fields harms the effectiveness of your article, and can completely break it if significant enough. Getting good with these will help you during all your projects on this site.
Now let's talk about your concept.
This is a guitar that kills people and makes zombies that can also kill people. This isn't a great foundation for your piece, and there's no real narrative direction to support it. Generally, SCPs who try to ride on their ability to kill alone don't do very well here because most story-telling involving it usually takes the form of "interaction->someone dies." I strongly recommend that you bring this concept to the Brainstorming forum. While the users there might encourage you to radically change the abilities of your SCP, they might be able to provide ideas that end up being even better than what you have right now.
In summary. The clinical tone and grammar in this article needs a lot of improvement, and the concept can't really stand on its own at the moment. The reading of other articles and self-review runs are what I recommend for the first two issues. Brainstorming with peers on this site is what I recommend for the last one. Good luck!
