"He did a silly thing," North Carolina coach Roy Williams told ESPN at ACC media day Wednesday. "That's what it was. One of his greatest characteristics is his competitiveness."
Pinson said Berry broke his hand while playing NBA 2K18. "It was just a freak accident," he said.
Pinson said Berry told him something was wrong with the hand before they went to bed, but he assumed it wasn't serious.
Williams told ESPN that he is uncertain how long Berry will be out, but the initial prognosis was approximately four weeks. The Tar Heels open the regular season on Nov. 10 in Chapel Hill against Northern Iowa.
The Tar Heels have tried to adjust in practice without Berry.
Pinson said he's played point guard in the team's last two practices, which has pushed Seventh Woods and Kenny Williams, who are also vying to replace Berry during his absence.
"[Williams] always wants three point guards after the Kendall Marshall incident," Pinson said.
Marshall suffered a broken wrist during the 2012 NCAA tournament, which derailed UNC's title aspirations.
Berry was the Most Outstanding Player at the Final Four last season and helped lead the Tar Heels to the national title. He had 22 points in the national championship game victory over Gonzaga.
Berry averaged 14.7 points and 3.6 assists last season and was named a preseason first-team All-American by ESPN on Monday. Williams said point guard duties will be split among freshman Jalek Felton, sophomore Seventh Woods and Pinson.
North Carolina has lost several key pieces from last year's team. Justin Jackson and Tony Bradley left early for the NBA, and Kennedy Meeks, Isaiah Hicks and Nate Britt were all seniors.
ESPN's Myron Medcalf contributed to this report.