My Panasonic TH-42PX75U will not turn on. It shows no sign of power i.e. red blinking light that I keep hearing about.

Probably the very common failure of the main power supply or one of its outputs. The power supply board is normally easy to identify; it will be a smaller board but with larger parts on it and is normally plug-connected so shouldn't require soldering at all. Panasonic may have new stock or repaired supplies on an exchange basis; call them. The failure mode is mostly caused by the failure of a few cheap components which can be found by any tech owning an RCL meter with loss readouts. I've repaired many hundreds of this type of supply for a dollar or two in parts and not a whole lot of time. It was a nice sideline while I still did this kind of work.