Because these files are specific to older hardware and firmware versions, you can find the .rar package containing the loader and the 2021 channel list by searching these reliable platforms:

Before uploading a new channel list, use the receiver's menu to export your current settings to a USB drive as a backup.

hardware version to avoid "bricking" the device (making it unbootable).

Channel lists for these devices are usually in or .abs format. Ensure the file you download specifically matches the Train 777 mini