CHICAGO – It was September 1985 when a 24-year-old Brian Dunn knotted his skinny leather tie and set off to begin a job as a sales clerk inside a small electronics store in Minnetonka, Minn., named Best Buy.

He was unemployed and took the paid-on-commission job after his mother — an employee in the chain’s accounting department — convinced him to give the company a try.

“I wasn’t sure I’d make it through the holiday season that year,” he said. “I remember going home with the sore retail feet.”

On Wednesday — almost 24 years after his first day selling video cassettes and speakers the size of chairs — Dunn became chief executive of Best Buy Co. Inc., which has grown to become the world’s largest consumer electronics chain.

“I was there,” he said during a speech before shareholders at the company’s annual meeting in suburban Minneapolis. “For the good, the bad and the ugly and everything in between. And I remember, and I will insist we remember the lessons we learned from the challenges and changes along the way.”

The 49-year-old (who eventually ditched the self-described “Miami Vice” look as he moved through the company’s ranks and now has a teenage son who works as one of Best Buy’s ubiquitous “blue shirts”) has heady challenges ahead.

Despite the demise of its rival Circuit City, same-store sales are down for the third straight quarter at his longtime employer. The company’s corporate office has hundreds of empty desks after a voluntary buyout.

And heavyweights Amazon.com, Wal-Mart Stores Inc. and Costco Wholesale Corp. all have their sights set the company’s core business.

“I think he certainly has his hands full,” Morningstar analyst Brady Lemos said.