my eufy robot vacuum is making a horrible grinding noise and then stops with four beeps

Yeah, the four-beep solid red light error is classic—something's jammed in the rolling brush.

1. Turn the RoboVac off using the main power switch on the bottom.
2. Flip it over. Pull the two release tabs on the brush guard to unlock it.
3. Lift out the rolling brush. You'll probably find a hair tourniquet or a chunk of debris wrapped around the ends.
4. Use the provided cleaning tool or a pair of scissors to cut and remove all the tangled material.
5. Reinstall the brush by inserting the fixed (non-gear) end first, then clicking the other end into place. Press down to snap the guard closed.
6. Turn the power back on.

If that didn't work: The side brush might also be stuck (two-beep error). Turn it off and remove any hair or string wrapped around the side brush axles.

Heads up: Clean the rolling brush weekly to prevent this. Long-haired pet owners, you know the drill.