| Symptom | Likely Cause | Solution | | :--- | :--- | :--- | | Updater says “Device not found” | Charge-only USB cable, or controller in wrong mode | Swap cable, ensure controller is ON and not in Bluetooth mode. Try a different USB port. | | Update stalls at 37% | Bluetooth interference or USB disconnection | Reconnect cable, restart updater, and run “Recovery Mode”: hold L1+R2+Home for 5s before connecting. | | Controller is unresponsive after update (no LED) | Corrupted bootloader | This is rare. Perform a hard reset: Insert a paperclip into the reset pinhole near L1 for 10s. Then reflash using the PC recovery tool. | | Buttons reversed or sticks inverted | Wrong firmware variant (e.g., N-SL Pro vs. N-SL Lite) | Download the correct firmware. The serial number prefix (NSL-2xxx vs NSL-3xxx) indicates the model. |