Please stop using this, it's been explained that your OEM left remnants of OpenWrt information in their firmware. Continuing to post this is only causing confusion and doesn't magically make the OEM firmware become official.
Flash instruction: Vendor firmware is based on OpenWrt CC release. Use the "factory" image directly in GUI (make sure to uncheck "keep settings")
As I have explained several times, when I try to upgrade via the GUI, I select update from file to use a file on a USB attached pen, but when I click on Browse. Chrome closes down, that is why I want to update from the command line rather than the GUI.
The commit only shows GUI instructions. Feel free to email the person listed in the commit to ask for CLI instructions.
(Again, your OEM firmware isn't OpenWrt, so we cannot guess command line instructions. You can try at your own risk, but I'm reluctant to provide any untested directions that could brick your device.)
Edit:
This was also new information.
Usually the "Browse" button in a browser is for the local machine's file system, not for a USB inserted into a remote device. Additionally, it's unclear why one would transfer the firmware to USB or not use the [local] machine it was downloaded to. Therefore, we don't why you're using a USB flash drive for any purpose.