Ensure the extracted files (usually .zip , .sfc , .bin ) are placed in the correct ROMs folder on the SD card ( /Roms/[SystemName]/ ) and that you have BIOS files installed for systems like PS1.

If the device won't boot, you may need to reflash the official Miyoo firmware to fix the "wrong" file.

when you try to open the rar or use the file? Are you using the stock SD card that came with the device?

Here is how to address this issue based on common troubleshooting steps for that device:

Corrupted downloads are common. Try downloading the .rar file again, preferably using a different browser or a download manager to ensure file integrity.

It sounds like you may have downloaded a corrupted or incorrect ROM or firmware file ( .rar ) for your handheld, which is common if sources aren't verified.

Use 7-Zip (Windows) or The Unarchiver (Mac) to extract the .rar file. Do not use built-in Windows extractors, as they often fail with complex nested rar files.