That grinding is usually a paper jam or a foreign object caught in the paper path. Turn it off and unplug it immediately.
First, clear any obvious jam. Open all doors—the front cartridge door and the rear output door. Gently remove any crumpled paper you can see. Pull it straight out in the direction the paper travels. Don't yank it sideways.
If you don't see paper, the noise might be from the pickup assembly. Flip the printer on its side (power off and unplugged). Release the blue latch and remove the panel. Shine a light in and look for a torn piece of paper label, a staple, or anything stuck around the rollers. Remove any debris.
If that didn't work: A gear or internal mechanism could be damaged. If the noise persists after clearing all obstructions, you'll need to contact HP support for service.
Heads up: To prevent this, always fan paper before loading, don't overfill the tray, and never use damaged paper or paper with staples or stickers.