“bc” blinks on the LCD panel.
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A misoperation has occurred with the camera, lens, or flash unit.
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Remove and reload the battery. If “bc” turns off, camera operation will be normal.
• If “bc” still continues to blink, the camera, lens, or flash unit is faulty. Take the camera and any attached lens and flash unit to your nearest Canon Service
Center.

Czyli po naszemu - wyciągnij i włóż baterię. Jak nie pomoże - masz problem.