Young people dressed in an array of colorful clothes covered with patches climbed atop a paint-splattered set in the Booth Theatre at Boston University Friday.

Fans of BROCKHAMPTON were getting antsy. It had been 45 minutes since the show’s scheduled start time Saturday night, and there was still no sign of the band. Any glimmer of action earned an exaggerated reaction from the audience. An audio recording of Agganis Arena safety protocol set off roaring cheers.