Update: 2018-07-19 Preview：1303 For:PA6 、
Step 1: Open bowser and enter plc.tendawifi.com in address bar to login the setup page.
Step 2: Choose “Administration” > “Device Management” > “Firmware Upgrade”. Tap “Upgrade” to upload the firmware.
Note: Please reset the device after firmware upgrade is finished.
Will it help you?