Frontman James Hetfield was left fuming when his microphone failed to work at the start of the band's performance with Lady Gaga at the ceremony last Sunday (12Feb17).

Following the performance, James was seen knocking over his mic stand and throwing his guitar off stage, with bandmate Lars Ulrich telling James Corden that the singer was "livid" with the error.

Now Ken has come forward to publicly apologise to the band, admitting to The Associated Press: "These kinds of things are horrible when they happen. That's one of the risks of live television.

"Obviously, we apologise to the band."

It had been thought the microphone was simply dead, but Ken added in the interview that his crew had a different theory about what caused the issue.

"My guys say that the mic cable was connected," he said. "My guys' theory was that ... one of the extras (on stage) accidentally kicked out the cable that went to the mic."

Despite how it happened, Ken called the problem "awful", and admitted it had a drastic effect on him as he has worked with Metallica for so many years. "You hurt," he said, labelling it personally upsetting.

The Metallica microphone mishap wasn't the only glitch during Sunday's ceremony. They also misidentified lifetime achievement award honoree Shirley Caesar, showing a picture of another gospel singer CeCe Winans instead of Shirley during a video montage.

Explaining what happened, Ken said he had been looking for footage to put in the clip, and opted to use a classic performance of CeCe, Shirley and Whitney Houston. However, instead of Shirley being shown, CeCe was focused on, and as he didn't have time to check the tape before it was aired, the error was shown as part of the live broadcast.

"We obviously want to apologise to Shirley Caesar," he said. "It's unfortunate that happened. When you do a three-and-a-half hour live show, it's fraught with danger. It was an adventurous show in many ways."

Another headline-grabbing incident during the ceremony saw Adele restart her tribute to George Michael as she was unhappy with how it sounded.