While I have been inside quite a few plasma displays from an engineering standpoint, and certainly understand their workings, I don't "work on them for a living" and so I'm not aware if there is common problem that may cause this on your model.

That said, there are not that many different types of symptoms (i.e. no power, no sound, shuts down, display anomalies), there can be however, hundreds of causes.

Unless you have electronic troubleshooting experience and experience working on opened-up, AC powered equipment, there probably is not much you can do. A symptom like you describe could be caused by an internal intermittent connection, component failure, or display failure.

Due to the way the television processes and distributes the signal inside the set, and to the actual glass display itself, multiple "ribbon cables" are often used and can be prone to intermittent connections. Sometimes they only require re-seating - other times replacement or more creative solutions.

Something that you can do to see if the problem may be an intermittent connection is to tap around the rear perimeter of the cabinet, with the set turned on, and see if the problem changes or disappears. Of course, don't tap too hard - it is a glass display. :)

If it appears like that may be the case, you could then pursue having it repaired. If it's component failure, troubleshooting and parts can get expensive but may be worth it. Display failure itself is basically a no-go unless it is covered under warranty.

It's unfortunate but because of the disposable prices of consumer electronics, and the mfgs. lack of replacement parts and service literature, most of the service industry disappeared. Now with higher priced, and repairable, products appearing again from at least the larger mfgs, the selection of available service facilities can often be quite limited.