If the chip is empty, it will automatically enter download mode when you connect it to the USB port. Otherwise, you may need to use the "force-download" tool.
To flash the firmware, you need to obtain AC692x_SDK_release_V2.6.3 from a reseller of JieLi.
Once you've installed the SDK, copy sdk.app and flashme.bat files to AC692x_SDK_release_V2.6.3\apps\download\post_build\flash folder.
You can then flash the firmware by running flashme.bat as an administrator, while the device is connected to the computer."