Firing her PR team, and hiring a new one mid-trial, was not effective and done too late to save her image. Throughout the trial and with the court finding that she published false and defamatory allegations, Heard developed a reputation as someone lacking credibility. Without credibility, an individual or brand has little to build on. When you lose trust, your character is harmed.
Here are a few reasons why I feel that Amber Heard lost her credibility with the public, ultimately losing the case.