Tenda - Ph3 Firmware ((free))
This is rare but serious. Perform the process described in Method 2. If the LED remains off after 10 minutes, contact Tenda support via their RMA portal. If within warranty, they will replace the unit.
Officially, the Tenda Powerline Utility is Windows-only. Mac and Linux users should borrow a Windows PC or use a virtual machine (VirtualBox with Windows guest). The offline recovery method via Ethernet and web browser may work on macOS with a static IP, but it is not guaranteed. tenda ph3 firmware
Mixing AV1000 adapters with older AV600 units will likely drop the entire network's speed to the lower 600Mbps standard. The This is rare but serious