DIAGNOSIS That's the sound of the printhead carriage hitting an obstruction or moving on a dry track. Most often, it's a stuck piece of paper, a forgotten packing material, or the carriage guide rail has no lubrication.
FIX Immediately cancel any print job and turn the printer off. Open the front cartridge access door. The printhead carriage should be in the center. Manually inspect the path for any scraps of paper, the little orange plastic tape from new cartridges, or other debris. Gently move the carriage by hand from side to side—if it's stiff, you've found the issue. Power the printer back on; it will often home itself and the noise may stop if the obstruction was cleared.
IF THAT DIDN'T WORK If the carriage moves freely but still grinds when powered, the encoder strip (the clear plastic strip behind the carriage) is likely dirty. With the printer off, use a dry cotton swab to very gently wipe it clean. Do not use liquids, as they can ruin the strip.
HEADS UP Never force the carriage if it's electronically locked. If it won't budge with gentle pressure, turn the printer on first, let it try to initialize, then turn it off again—the lock might release. Forcing it can break the plastic gear train inside.