This thread is very informative but has not solved an issue I'm facing with my set now. Here are my symptoms:
1) Plug in the TV. It shows a black screen with an amber LED.
2) Also, plug in the TV. Starts with an amber LED but does load the boot screen and get to a blue LED. Sometimes the screen has a "Detecting..." box in the top middle, indicating that it is looking for video signals. Regardless, the TV begins displaying garbage vertical lines. Unplugging and immediately replugging the TV repeats these symptoms.
I haven't been able to track down specific known symptoms for when the main board or the power supply go bust. I have attempted to load the different firmware listed in this threat. Using the same memory stick, the TV does not recognize "TX-42F430S - v1.4.0 - editted (1)" or "01_OSD_FW_V1.4.0", but it does recognize "SusanII_v1.6.3". Instructions I followed are are:
1) Unplug the TV.
2) Put the USB drive in the service port.
3) Plug in the TV.
4) Wait 30 seconds. The LED should start amber and then become a flashing purple.
5) Wait about 5 minutes (but possibly also 7-8 hours) for the flashing purple LED to become blue.
6) Disconnect the USB drive.
7) Press the power button to turn on the TV.
Following these instructions, the custom firmware did not get past the amber LED; it flashed purple once and then stayed amber; the TV also does this when no USB sticks are plugged in. Susan II got past the amber LED to the flashing purple, but after about 8 hours, it didn't stop flashing, and attempts to turn on the TV resulted in the first symptoms, about the Amber LED of Death and the "Detecting..." box and vertical lines.
Based on post #5731, I attempt to replace all "exit 1" with "exit 0" in the Susan II firmware. This did not have any impact on the symptom.
You're more than welcome to help me diagnose and fix this broken TV if you want.
Thanks in advance for all help!