my s7 is vacuuming fine but it won't map my house at all, the map is just a blank grey blob.

Diagnosis

The "grey blob" mapping failure on the Roborock S7 is a classic symptom of a LiDAR (Light Detection and Ranging) failure. The S7 relies on a rotating laser turret on top of the chassis to bounce beams off walls and furniture to calculate distance. When the map appears as a featureless grey mass, it means the robot is moving and the wheels are reporting distance (odometry), but the laser sensor is not returning any spatial data to the processor. Essentially, the robot is "blind" while moving.

This typically happens for one of three reasons: a physical obstruction (like a stray hair or piece of string) is jamming the rotating laser head, the LiDAR motor has suffered a mechanical failure, or the optical lens is coated in a layer of fine dust that prevents the laser from reflecting back. You can confirm this by listening closely to the top of the robot when it starts a cleaning cycle; if you don't hear a faint, high-pitched whirring sound or if you see the laser turret not spinning, the hardware is stalled.

How to Fix It

To resolve a stalled LiDAR sensor and restore mapping capabilities, follow these precise steps:

1. Power down the Roborock S7 completely by pressing and holding the power button until the LEDs turn off.
2. Inspect the LiDAR turret (the circular protrusion on top). Use a can of compressed air to blow out the gap between the rotating laser head and the chassis. Aim the nozzle at a 45-degree angle to clear any debris that may be wedged in the track.
3. Take a dry, lint-free microfiber cloth and gently wipe the exterior of the clear plastic dome. Avoid using chemical cleaners or isopropyl alcohol on the dome, as these can strip the anti-reflective coating.
4. Perform a "manual spin test." Use a thin toothpick or a cotton swab to very gently nudge the rotating laser head. It should spin 360 degrees with zero resistance. If you feel a "click" or a hard stop, there is a foreign object lodged in the gear mechanism.
5. Reset the mapping software. Open the Roborock app, go to Settings > Map Management, and delete the current "grey blob" map. This forces the robot to start a fresh SLAM (Simultaneous Localization and Mapping) sequence.
6. Place the robot on the dock and initiate a "Full Clean" run. Do not interfere with the robot or pick it up during the first 20 minutes of this run, as this allows the LiDAR to calibrate the room boundaries.

If That Didn't Work

• Hard Reset the System: Press and hold the Reset button (located near the Wi-Fi indicator) using a paperclip for 5 seconds. This clears the temporary cache of the navigation system and can often kickstart a stalled LiDAR motor that has entered a "protection mode" due to a previous jam.
• Check for "Invisible" Obstructions: Ensure you don't have floor-to-ceiling mirrors or highly reflective chrome furniture at floor level. The S7's laser can bounce off these surfaces, creating "ghost rooms" or causing the mapping algorithm to crash, resulting in a blank map. Cover mirrors with a towel temporarily to see if the map begins to populate.
• Replace the LiDAR Motor: If the turret does not spin even after cleaning, the small DC motor inside the turret has likely burnt out. You will need to purchase a replacement LiDAR Motor assembly (Part #S7-LDS-MOT). This requires removing the top cover of the robot and swapping the motor unit.
• Firmware Rollback/Update: Check the app for a pending firmware update. Occasionally, a corrupted update can cause the LiDAR to stop communicating with the motherboard. If an update is available, install it; if you recently updated, try a factory reset to clear the firmware glitch.

Heads Up

• Avoid Wet Cleaning the Top: Never use a damp cloth or spray water on the LiDAR turret. Moisture can seep into the optical sensor and cause permanent fogging, which leads to mapping errors.
• Pet Hair Maintenance: If you have long-haired pets, the LiDAR gap is a magnet for floating fur. Use compressed air once a month to keep the turret clear of debris.
• Don't Force the Spin: When testing the laser head, apply minimal pressure. Forcing the disc can bend the internal axle, rendering the entire LiDAR assembly useless.
• Dock Placement: Always ensure the charging dock is on a flat, hard surface with 0.5 meters of clearance on either side. If the robot struggles to "home" due to poor dock placement, it can corrupt the saved map data.