GREENVILLE, South Carolina — Actor Hayden Panettiere died from an accidental overdose of several drugs, including fentanyl, and had been in rehab just weeks before, according to a coroner's report obtained by The Associated Press. Panettiere, 36, was found unresponsive in an apartment in Greenville, South Carolina, on Aug 16. Her on-and-off boyfriend Brian Hickerson and his brother Zach Hickerson were at the home. A combination of fentanyl and its chemical byproduct, as well as the anti-anxiety medication alprazolam, a muscle relaxer and a drug used to treat major depression and other serious mental health disorders, was found in…