Where the case sits thus far in my opinion:
The only evidence for self defense is Zimmerman's word and judgement... both of which have been shown to be false and questionable.
Despite Z's claim, Martin was not under the influence of drugs. Despite Z's claim, Martin did noy have anything wrong with him, nor was he up to no good. Despite Z's claim, Martin almost certainly did not return from behind the buildings at the T to circle Z's truck in a threatening manner. Despite Z's claim, Martin almost certainly did not approach Z with his hand in his waistband, then while holding something in his hand.
Despite Z's claim, it is unbelievable that Z's did not remember the street name, and even more unbelievable that he was searching behind the buildings for a house number. Despite Z's claim to the contrary, we know from the location of the fight that Z continued to pursue Martin all the way to the point of the fight. Despite Z's claim we know that Martin did not knock Z down and begin pounding his head on the sidewalk at the T intersection. Despite Z's claim, we know that Martin did not punch him in the face twenty times, or smother him, or muffle his cries, and it is questionable whether his head ever hit the sidewalk at all.
We know that there was a fight of some kind. We don't know who started it, we don't know who was winning, but we do know that neither party was particularly injured prior to the gunshot. We know that Zimmerman apparently never even tried to physically defend himself. We know, based on witness testimony and physical evidence, that Zimmerman plays fast and loose with the facts.
We know that Martin was scared and had tried to avoid the fight altogether. We know, based on physical evidence and witness testimony, that Zimmerman pursued Martin over and over and over again. He pursued him when he entered the property, he pursued at the clubhouse, he pursued down Twin Tree lane, he pursued him between the buildings, he pursued until they met.
At SOME point Zimmerman must advance some kind of evidence to support his claim that this was self-defense. He's the one making this claim, and his team needs to support it in some way. So far they have not done so. So far all we have is the statement of a guy with (at best) terrible judgement and a track record for lying.