Sony WEGA KE-P42XS1 will not boot up

PLEASE HELP !!

I have a Sony WEGA plasma KE-P42XS1 and I entered the test mode by pressing the keys on the remote: {display} -> [5] -> {up vol} -> {TV}. (The intent was to fix a problem with the horizontal position of the picture, but I never got that far.)

I got some big characters with Tnnn on the upper right. The last thing I did was hit the sequence {display} -> [5] -> {DN vol} -> {TV} and nothing happened. I decided to stop everything and power down the TV and power up. I was horrified to discover that the TV would not initialise. I only had one power light and no other lights (stdby was off). I disconnected the power to the TV, waited a few minutes, reconnected power and tried to turn it on, but all I got was the one glowing power LED as before. TV was dark. No other LEDs were on. Remote did and does nothing to the TV (remote itself is working). I even cycled the power switch on the right side of the set with no results other than the power led cycling on and off as I pressed the power switch on and off.

My TV is not under warranty. I am an electronics technician and I have the service manual, but it says nothing about the service codes. I got that info from another forum. Now I know why the service manual said nothing about the codes.

I figure that the next thing I can try is perform a firmware or software update, but I need the firmware file and the instructions or service bulletin that goes with it.

Can anyone help me ? (short of suggesting to take it to an authorized Sony service center)

Please advise.

I have an interesting question: If you were told to use (Display, 5, Vol +, TV), for what purpose did you use the same thing again, but modifying the commands that you used to get in to the service mode??

The big characters on the screen must have been an indication of something.

By using erroneous entries, and now not knowing what was done, it is possible that a wrong entry was commanded, and something is set in a way that is locking out the set from operating. Another thing that may have happened, is that by coincidence something else in the set failed.

When the set was new, if the problem was not present and it came up on its own, obviously there is some component that has become defective, and therefore an adjustment is not the solution. Proper servicing would be the solution.

If the uPC system in the set is locked out because of an erroneous entry, there is no way without changing the EPROM to one containing the default operation. With the default operation, the complete factory set up would have to be done, which has alignments that I doubt you would be able to do at home, unless you had all the necessary setup, experience, and factory setup and service manuals.

Your best bet is to take the set to the authorized Sony service rep for your area. If the set is more than about 3 years old, the replacement EPROM may no longer be available. In many of the models, the complete processor board has to be replaced if there is a fault, and then the complete factory alignment must be performed. They do not support to service the processor board.

The EPROM is a high density surface mount device. I had a number of Plasma displays from Sony, where I was not able to have the parts any more. They recommended that the sets should be replaced for newer models.