Again, just because attorneys won't take a case which looks like a financial boondoggle from a case evaluation standpoint doesn't mean it didn't happen. They'd have to prove that there was some error in the forensic analysis, and that error not just suggests, but screams a different outcome.
I have to guess a lot because the particulars of the forensics are extremely vague by all public accounts.
And speaking as an attorney, we don't decline cases like this because we think our potential client is right. We think about the resources we're going to have to put into the case vs. what we can get out of it unless we have some sort of grant money or outside backing.
That said, if you think police labs and forensics are fool-proof, and that all experts on behalf of the State tell the truth, give this a read:
https://en.wikipedia.org/wiki/Joyce_Gilchrist
The galling thing is that she didn't die in prison.