Last resort
OTA Xteink Unlocker
For locked Xteink devices that won't take an SD card flash.
Try SD card flashing first. It's simpler and needs no extra software. See the SD flashing steps — only reach for the Unlocker if your firmware won't flash from the SD card.
How it works
International Xteink devices (including those from AliExpress) ship with USB flashing disabled. Xteink Unlocker turns your computer into a local hotspot that intercepts the device's official update channel and serves CrossPoint or Crossink instead of the stock firmware — installing community firmware entirely over the air. It does not unlock your USB flashing capabilities, but it does allow flashing of custom firmware.
Available for macOS, Windows, and Linux, including ARM64 builds for Raspberry Pi OS. The tool is open sourced on GitHub.
Download the Unlocker
Use at your own risk. USB flashing will still be disabled, but you can use this tool to flash updated firmware any time.