9 times out of 10 start ups no voice ,it comes on 5 min.later approx gently tap rear of cabinet sometimes works

Have your drive belt replaced (sometimes called the auxiliary or serpentine belt) when it slips it creates a screeching noise and it's also a sign that it's going to fail (snap).
These can run the alternator and power steering so you should change it as a preventative measure.

check fuel pump maybe bad pump or connection

Check out this link. Your symptoms sound like the infamous failed antitheft system known as passlock. This system comes standard on your vehicle, and is known to fail and cause this exact problem... http://vatspasslockpasskeysecurityhelp.yolasite.com/

This happened to me its probably too late for you but might help others. what i did to fix this is, I put the tv onto a radio channel (with no picture) and about 10 mins later i turned the volume down and realised the screen was still on as the volume bar showed up. so i guessed it the problem was to do with light so i went on the menu and went into features and turned the backlight onto minimum and the tv has been fine since. hope this helps!

bad connection , solder inside have to be done again

sounds like your fuel pump is going out. One thought might be that the fuel filter is causing enough resistance to over heat the pump. I would check the fule pressure to determine a free flow of fuel.

DLP --- need to exchange the thermostat.
LCD --- replace the Main Board.
PDP --- need to check Power Board or Y-Main

i suspect you have a blockage in the dryer duct - take top and rear cabinet off and the dfuct is exposed - it often gets blocked with lint

weak power supply

the power regulater for your system have a short take it to a tech to have him fix it orelse you might cause further damage.