is it possible to restore the factory defaults of the PLC?
After an unsuccessful atempt to update the PLC certificates the management portal is not accessible anymore.
Yes, it is possible. If the administration web on 8443 port is not accessible, you can restore the firmware this way:
1) switch off PLC
2) remove the cover marked ETH1 and under it you will find 2 DIP switches
3) Switch 1 remains in the OFF position, set switch 2 to the ON position (see attached )
4) Switch on the PLC power supply and after the PLC boots, switch switch 2 back to the OFF position
5) Launch a browser with port 8080 (typically 192.168.134.178:8080) - the browser will not need a password
6) Download the new firmware from ftp server by Firmware Updater. The name of file is teco_imx6ul.tfw, version of firmware is 3.9 (it should be published today or tomorrow, at max. within several days.
7) And upload it to the PLC via the Update page in the browser. If it is possible to connect PLC via Firmware Updater, you can make an update using this tool.
8) when it is loaded, take out the last time and turn on the power (attention !! both DIP switches has to be in OFF position).
This question is solved.