1. Introduction
This manual provides detailed instructions for the installation, setup, operation, and maintenance of your eLinkSmart YL-MD121 Smart Door Lock. This device integrates advanced security features including a 2K camera, video doorbell, multiple unlocking methods, and built-in Wi-Fi for remote access. Please read this manual thoroughly before installation and use to ensure proper function and safety.

Figure 1: eLinkSmart YL-MD121 Smart Door Lock with Camera and Keypad
2. Package Contents
Verify that all components are present in the package:
- Smart WiFi Deadbolt Lock (Exterior and Interior Assemblies)
- 7.4V 5000mAh 37Wh Rechargeable Battery
- Keys x 4
- Installation Hardware (screws, bolts, etc.)
- User Manual (this document)
- USB-C Charging Cable
3. Product Overview
The eLinkSmart YL-MD121 is a comprehensive smart door lock system designed for enhanced home security and convenience.
Key Features:
- Integrated 2K Camera: HD 2K camera with f/1.6 lens for clear visibility, including night vision.
- Video Doorbell: Allows two-way audio communication with visitors.
- PIR Motion Detection: Advanced radar technology senses motion up to 2 meters, sending alerts and recording video.
- Multiple Unlocking Methods: Fingerprint, keypad code, mobile app, physical key, and voice control (via Alexa).
- Built-in Wi-Fi: No additional hub required for remote access and control via the Tuya App.
- Long-Lasting Battery: Built-in 37Wh rechargeable battery provides up to 365 days of standby time (in non-Wi-Fi mode).
- Easy DIY Installation: Compatible with most standard deadbolt spacings, typically installable within 15 minutes without drilling.
- Weather Resistance: IP53 rated, operating in temperatures from -22°F to 158°F.

Figure 2: Two-Way Audio and Video Doorbell Functionality

Figure 3: 2K 180° Panoramic Camera View
4. Installation Guide
Follow these steps to install your eLinkSmart YL-MD121 Smart Door Lock. Ensure your door meets the specified dimensions:
- Prepare Your Door: Remove any existing deadbolt hardware. Ensure your door's backset is 2-3/8" (60mm) or 2-3/4" (70mm), door hole diameter is 2-1/8" (54mm) or 1-1/2" (38mm), and door thickness is 1-3/8" (35mm) to 2-1/8" (55mm).
- Install the Latch: Insert the latch into the door edge. Secure it with screws.
- Install the Exterior Assembly: Route the cables through the door hole and align the exterior assembly with the latch.
- Install the Interior Mounting Plate: Secure the interior mounting plate to the exterior assembly using the provided screws.
- Connect Cables and Install Interior Assembly: Connect the cables from the exterior assembly to the interior assembly. Carefully tuck the cables into the door. Attach the interior assembly to the mounting plate.
- Insert Battery: Place the rechargeable battery into the interior assembly.

Figure 4: Door Dimensions and Compatibility for Installation
Installation Video:
Video 1: Step-by-step guide on correctly installing the lock latch.
5. Setup
After physical installation, set up the smart lock with the Tuya App.
- Download the Tuya App: Search for "Tuya Smart" in your mobile app store and install it.
- Create an Account: Follow the in-app instructions to create or log in to your Tuya account.
- Enter Pairing Mode: On the lock's keypad, enter the administrator mode (refer to the included user manual for specific steps). Follow the voice prompts to enter Wi-Fi pairing mode.
- Add Device in App: In the Tuya App, tap '+' to add a new device. The app should automatically detect the lock in pairing mode. Follow the on-screen instructions to connect the lock to your 2.4GHz Wi-Fi network.
- Configure Settings: Once connected, you can configure various settings such as user management (fingerprints, passcodes), auto-lock duration, and motion detection sensitivity.

Figure 5: Built-in Wi-Fi and Compatibility with Tuya Smart, Smart Life, and Amazon Alexa

Figure 6: Remote Control and Monitoring via App
6. Operating Instructions
The eLinkSmart YL-MD121 offers multiple convenient ways to unlock and monitor your door.
Unlocking Methods:
- Fingerprint Unlock: Place your registered finger on the fingerprint sensor. The lock will unlock in approximately 0.25 seconds with 99.99% accuracy. The lock supports up to 50 fingerprints.
- Keypad Code: Enter your programmed passcode on the keypad. The keypad supports anti-peeping passwords and is visible in low light.
- Mobile App Remote Control: Use the Tuya App to remotely unlock the door from anywhere with an internet connection.
- Physical Key: For traditional access or in case of emergency, use one of the provided physical keys.
- Voice Control: Integrate with Amazon Alexa or Google Assistant (via Tuya Smart/Smart Life) to unlock the door using voice commands.

Figure 7: Overview of 5 Unlocking Methods

Figure 8: Fingerprint Unlock Feature

Figure 9: Voice Control Integration
Video Doorbell and Monitoring:
- Video Doorbell: Visitors can press the doorbell button on the exterior assembly. You will receive a notification on your phone and can engage in two-way audio communication or view the live feed.
- PIR Motion Detection: The lock's sensor detects motion and sends alerts to your phone, recording video of activity at your doorstep.
- Live View: Access the 2K camera's live feed anytime through the Tuya App to monitor your front door.
Operation Videos:
Video 2: Demonstration of Smart Door Lock with Camera and Video Doorbell PIR Detection.
Video 3: Overview of Fingerprint, Keypad Code, and Long-Lasting Battery features.
7. Maintenance
- Battery Charging: The lock features a built-in rechargeable battery. When the battery level is low, you will receive an alert. Charge the battery using the provided USB-C cable. A full charge takes approximately 3-4 hours.
- Cleaning: Use a soft, dry cloth to clean the exterior of the lock. Avoid abrasive cleaners or solvents.
- Firmware Updates: Periodically check the Tuya App for firmware updates to ensure optimal performance and security.

Figure 10: Long-Lasting Rechargeable Battery

Figure 11: Charging the Rechargeable Smart Lock
8. Troubleshooting
If you encounter issues with your eLinkSmart YL-MD121, refer to the following common solutions:
- Lock Not Responding: Check the battery level. If low, recharge the battery. Ensure the interior and exterior assemblies are properly connected.
- Fingerprint Not Recognized: Ensure your finger is clean and dry. Re-register your fingerprint if issues persist.
- Wi-Fi Connectivity Issues: Ensure your Wi-Fi network is 2.4GHz. Check your router's signal strength at the door. Restart the lock and your router.
- App Remote Unlock Not Working: Verify the lock is connected to Wi-Fi and your phone has an internet connection. Check app permissions.
- Auto-Lock Feature: If the auto-lock feature is not desired or needs adjustment, access the settings through the Tuya App or the lock's administrator menu.
- Camera Image Quality: While the camera is 2K, direct sunlight can affect image clarity. Check app settings for any available image adjustments (e.g., contrast, brightness) if provided in future updates.
- No Motion Detection Notifications: Ensure PIR motion detection is enabled in the app settings and sensitivity is adjusted appropriately.
9. Specifications
| Feature | Specification |
|---|---|
| Brand | eLinkSmart |
| Model Name | YL-MD121 |
| Lock Type | Biometric |
| Material | Zinc |
| Color | Black |
| Item Dimensions (L x W x H) | 7.7 x 3 x 1.2 inches |
| Item Weight | 3.59 pounds (1.63 Kilograms) |
| Special Features | Tuya App, PIR Motion, Video Doorbell, 2K Camera |
| Connectivity Protocol | Wi-Fi (2.4GHz) |
| Control Method | App, Keypad, Fingerprint, Key, Voice (Alexa) |
| Battery | 7.4V 5000mAh 37Wh Rechargeable Battery |
| Weather Resistance | IP53 Rating, -22°F to 158°F |

Figure 12: Weather Resistance Features

Figure 13: Durability Test Information
10. Warranty and Support
The eLinkSmart YL-MD121 Smart Door Lock comes with a 24-month protection plan. For any questions, technical assistance, or warranty claims, please contact eLinkSmart customer support. Round-the-clock customer support is available to assist you.
For further assistance, please refer to the contact information provided in your product packaging or on the official eLinkSmart website.





