Angular2 - Material2 - Custom Checkbox

I'm working on creating a custom checkbox based on the angular material2 project. Everything seems to be working at first but when I update model values in code, the checkbox does not un-check even though angular registers the change. See the plunker for a demo.

The relevant code to update the model values is:

private _parentValue:bool = false;
get parentValue()
{
    return this._parentValue;
}
set parentValue(val)
{
    this._parentValue = coerceBooleanProperty(val);

    this.value1 = this._parentValue;
    this.value2 = this._parentValue;
    this.value3 = this._parentValue;
}

I apologize in advance if I have done something incorrect here as this is my first time posting to stack overflow.