B530 Service port (is it an ex-link port)

[juusso]

Yes, true, "service"is right port for you especially if you get debug info on terminal. B530 is low budget TV without any bonuses like MediaPlayer, content library apps and ethernet port. I think you can try to get root, but i do not know what to do with rooted B530.
Did you try to enter "debug" according wiki page about ExLink - just after you could enter commands...

You can`t power on TV from rs232, just if you get success and root it, you be able to power off it only. IMHO.

[erdem_ua]

What is your baud rate? I think lower B series TVs uses lower baud speeds like 9600 instead of 115200.
You can also try to push emergency button on mainboard to enable debug mode.

[juusso]

You can`t do it, not supported by hardware.