I bought the 65in Q90T in March and today I was watching TV, the TV turned off and now it turns on until the screen lights up and then turns off it self, it does this every 5 seconds when plugged in, the TV picture doesn't even load before turning off.
I also have a Panasonic for 5 years and no issues.
I have had a Q90 series TV for 10 months with no similar problems. Perhaps the set is dodgy. Have you tried doing a software upgrade just in case. I've had quite a few Samsung TVs and phones and never had any quality issues - apart from a phone case that stopped working.