M1Active 520 light turns red and vibrates. Is this a power supply issue?

Hi all. I've had these studio monitors for several years with zero problems. I recently moved from the US to South Africa and brought these along figuring I wouldn't have an issue since these are dual voltage.

I changed the AC voltage selector on the back to 220-240V. I was eager to test them out and I haven't gotten the kettle cords with the South African plug yet so I hastily used a US to SA converter. It stays blue for a few seconds them immediately goes bezerk, turns red and makes a rapid pulsing noise.

So I'm obviously thinking it's not that they need to be serviced, but I need the proper SA cords plugged into a surge protected power strip. Can anyone confirm? I find it hard to believe they might've both been damaged in transport because they were sent by air freight through a corporate employer. Any info would be appreciated.
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