Hi there and welcome
This code usually points to a scan board issue though on occasion it can be thrown up spuriously so please do this first
Unplug the set from the wallpower
Press the on/off switch for 60 seconds after doing the above
Unplug all the inputs from the back of the set
Wait 1 hour
Re-plug the set back in again.
Does it still not start and flashes the power led 7 times?
If so, then the problem you have is failed scan boards, The drawback of that is that this has to be verified using a meter so the board can be identified and then replaced.
this issue would be covered by the warranty if this is still valid and they can do the testing for you, else you would need to pay for the repair yourself.
Let me know though how you go so far with my instructions and we can look at your options.