LG 55LM960v won't power on

I have a LG 55LM960v and my GF watched TV and it suddenly turned off og wouldn't power on again.

Normal startup process for this tv is standby light is red, when powered on you hear an click and standby light blinks and then the tv on.

Now you hear the click, but isn't powering on, standby light blinks as normal and after 4-5 seconds, it clicks and again and then it tries the same cyclus for 4-5 times and then stops trying to turn on and ends with standby light only.

So it seems like it tries to power up, but is getting an error, then retries for 4-5 times and then stays in standby mode.

I've tried to disconnect power for 20 minutes and reconnect, but no effect.

If I should open the TV and look at circuits to look for issues, which board should I check first and where do you think the defect is located?

Or any other alterntives? I've never repaired TV's so I just want to verify if this seems like panel issues and simple power/circuts issues.