SCP Foundation

SCP-XXXX is to be contained in a standard containment cell.

This is a little too brief- which site is it located on? What kind of security clearance is required to experiment on it? Just some ideas.
'cell' isn't really the correct terminology here- the Foundation is not a prison, and furthermore a cell would be far too large for what is literally an XBox in its inactive state.
SCP-XXXX is to be contained in a standard Safe object locker on Site-[#]. Experiments involving SCP-XXXX require Level-[#] security clearance or above.
Just skim-reading, I notice that your description is structured really oddly. It's by no means mandatory, but people will generally organise descriptions as such: what it is, what it does, where it came from. The impact of saying what it is and then where it came from is that you have this weird jarring sentence just by itself at the beginning that feels far too short. I'd suggest just simply swapping the 'where' and 'what it does' paragraphs.

SCP-XXXX is a standard XBox One, released by Microsoft. SCP-XXXX is not to be plugged into any outlets at all times.

A little nonclinical, grammar is off- and furthermore, don't use italics for emphasis. It looks silly.
SCP-XXXX is a Microsoft brand XBox One composed of typical, non-anomalous materials. At no point is SCP-XXXX to be provided with a power source.

SCP-XXXX was discovered on [REDACTED], in Berlin, Germany.

Dates are generally censored via blackboxing. Again- not mandatory by any means, just what the majority of people do.

SCP-XXXX was discovered in it's original packaging, showing no signs of change.

I think the 'showing no signs of change' is unnecessary and can be cut.
In fact, let me just rephrase that whole paragraph-
SCP-XXXX was discovered on █/█/████ in Berlin, Germany, still in its original branded packaging. SCP-XXX's anomalous properties were discovered approximately 24 hours following initial recovery.

classified as an SCP

They aren't actually really referred to as 'SCPs' or whatever- they are referred to by their designated item number (SCP-XXXX) or a vague idea of what it is e.g. 'entity', 'object', 'phenomenon'.

When SCP-XXXX is plugged into an outlet

This is a little nonclinical. Just try 'provided with electricity', maybe?

it begins to produce a loud whirring sound.

Accidental tense swap here, I think? Just 'it will produce a loud whirring sound' will suffice.

If SCP-XXXX is touched with any type of electrical conductor, such as a nail, or something is connected to it, such as a USB, an EMP [Electromagnetic Pulse] takes effect.

Okay, just to be clear- these are scientists. They don't need an example of an electrical conductor. Also- I feel as if the '[Electromagnetic Pulse]' would function better as a footnote.
I'm just going to tighten up the last few lines into my own version. It's more clinical, condensed and I think explains the anomaly much better. Hopefully this will give you an idea of how to proceed with this article's tone.
Upon contact with an electrical conductor or USB insertion, SCP-XXX will proceed to produce an EMP in a radius of 200 m, henceforth referred to as SCP-XXXX-1. SCP-XXXX-1 lasts for approximately 24 hours. Exiting SCP-XXXX-1's radius will result in all effects of the EMP being removed. However- re-entering with the same device will result in it being destroyed via [whatever you want to put here]. Destroyed items will then proceed to move towards SCP-XXXX in what appears to be a magnetic field. Upon the device making contact with the surface of the XBox, SCP-XXXX will proceed to reassemble various parts in order to take on a crude humanoid appearance.

Yeah, there's not much more to say here. The anomaly itself is… interesting, I suppose? I don't know enough about EMP's to judge whether or not the science of it is correct, but I do like the idea of something destroying electronics to build itself. Now please, stay calm until your writer's block passes, and then make this into something beautiful. I think you may have the chops to do it.