As suggested above there are many tips on to to upgrade firmware in the existing thread on this dongle → https://community.home-assistant.io/t/iteads-sonoff-zigbee-3-0-usb-dongle-plus-based-on-texas-instruments-cc2652p-20dbm-radio-mcu-now-sold-for-14-99/340705
Prerequisites key points are:
- Use a USB extension cable (due to USB plug on dongle being very short it might not fully insert).
- Install official CP210x USB to UART Bridge VCP Drivers from Silicon Labs if using Windows or Mac → https://www.silabs.com/developers/usb-to-uart-bridge-vcp-drivers
- Get the correct firmware image → https://github.com/Koenkk/Z-Stack-firmware/tree/master/coordinator/Z-Stack_3.x.0/bin
Adapters based on CC1352 or CC2652 chips can be flashed by putting them in the bootloader. After you have done this one of the following tools can be used to flash it. See your adapter manual on how to enable bootloader (boot mode) manually or use software that support automatic BSL mode for it.
Then upgrade firmware with one of these (ZigStar GW Multi tool and cc2538-bsl support auto BSL)
- cc2538-bsl (multi platform Python based command line tool with auto-BSL trigger) .
- llama-bslopen in new window (multi platform Python based CLI tool, a fork of cc2538-bsl).
- ZigStar GW Multi tool (multi platform portable GUI tool).
- Texas Instrumens FLASH PROGRAMMER 2 (Windows installer only, with auto-BSL trigger).