Check your USB port, let's make sure you don't have anything installed on it.
Try it again. If it doesn't start up normally, then disconnect the TV's power cord for a full 5 minutes to reset the TV's micro. Plug it back in and see if it recovers and starts working normally. If not, then the startup software is corrupted.
Ok, it's stuck on it's boot software then....
Sub is in stock, but you should check your TV's serial number to make sure it matches
Order that if the serial number fits the ones listed.
That will fix your start up problem.