Unless you are 100% certain that the PSU is indeed faulty, then most likely, is that the PSU is not faulty, due to the i2c bus that Plasma TV's would use.
The i2c bus is like an IDE connection on a computer, if one hdisk failed, the other would be used, but in a TV, the i2c bus, would report back a fault, and if there was anything that might cause issue, then the PSU would shut down, to prevent damage.
Depending on how long the TV remains on, before shutdown, or if indeed it comes on, then there is an internal diagnostic system available, to locate the fault area. You specify the part number required, but don't specify the fault. Just because it doesn't power up, doesn't mean the power supply is faulty, just that the power supply is shutting down, to prevent the set blowing up.
Google common faults regarding your model number. Check out diagnostic techniques. (Common ones are apply full volume, minimum bass, turn on from standby, then press up on the remote control 3 times)
A good one that is applicable to more people, if your Sky box is playing up, unplug it, press and hold backup button, on the box, apply power; It then downloads all its data and software, to the latest version.
A frozen/loss of picture on Sky, go into menu, picture settings I think, then diagnostics, it resets the LNB, and gives you the picture back. The same option used to say enter a code, and beeped at you.