I like the idea that you have presented here but I feel like your presentation killed it.
Firstly the exclamation points and the speech quotations took away from the poem as a whole. With short poems the layout is just as important and although this poem could be effective just the way you set it out makes me take it less seriously.
I suggest something simple like this

HELP ME.
please...

none came

I like this poem. It is short and to the point. In a way the second stanza reminds me Flutershy from My Little Pony. There is a part where she takes a deep breath like she is about to yell and instead her voice comes out in a quite whisper.

I just reread this poem while doing my review, and read "none came." Wow! What a defeating thought. Good job!

Poems like these always remind me of the ten word short story challenge, which always seems like so much, packed into so little, allowing you to imagine the context, the setting, everything. all this allows the reader to connect, and relate. This poem, which is so small, is really so big. All you need to see it, is an imagination.

The beauty and the struggle of short poetry is that it almost has to include some visual effects; it almost has to be concrete poetry.
You've already illustrated that here, to a point. Your affects are very surface, very obvious. Big letters and all caps for someone yelling, a bit smaller and no caps to illustrate a more quiet, desperate tone, and the finality of the last small words.

If you really want to make an impact, your visual affects have to have more symbolism than that. One of my favorite concrete poems is by e. e. cummings. http://bookpuddle.blogspot.com/2005/08/ ... ss-la.html This blogger does a great job of explaining all of the intricacies of that piece, as he sees it. Someone else could certainly interpret it differently.
But at one point he says, "A true thinker could speak about this poem until the world’s trees were bare." That is the kind of piece that you want. When you are writing a short poem, you have the freedom to leave it WIDE wide open. When someone reads what you have, they could imagine over a trillion different situations where someone needs help, and they can understand the feeling when no one is there to help.
However, if you want this to be a truly powerful piece, one that says something itself, instead of merely being a thought provoker, you have to do more with it. Maybe you will do that with a more profound, more complex visual; maybe you will decide to use different words. Take it to the next level.

Short and to the point. I like it!
There is so much left unsaid by these terse lines, so much left to the imagination, but in a good way.

One suggestion, because the 'Help Me!' evoked the desperation of someone in need of immediate (physical) assistance, perhaps you may consider changing the 'none came' to 'no one came'.