Troubleshooting if the Xiaomi Mi Smart Projector turns on but no picture or sound, please refer to the following steps:
1. Ensure all cables are securely connected to the projector and the input source. Loose connections can cause issues;
2. Make sure to select the correct input source on the projector using either the remote or the buttons on the device;
3. Check if the projector's volume is turned up. Use the remote or buttons on the projector to adjust the volume;
4. Test with a different device like a DVD player or gaming console to see if the problem persists, which can help identify if it's a projector or input source issue;
5. Turn off both the projector and the connected device, wait a few seconds, then turn them back on. Often, a quick restart can fix temporary issues;
6. Ensure the projector's firmware is up to date. Check for any available updates in the settings menu and install them if available. Updates may include fixes for audio or video issues;
7. If the problem persists, try resetting the projector to its factory settings. Keep in mind that this will erase all settings and data, so back up any important information first;
8. If the issue persists, contact your local after-sales for further assistance regarding this issue.