Toshiba flat screen problem

Had the same issue with a 58" Toshiba TV. After getting jerked around by customer support, they replaced it with a new one. If it is under warranty, contact Toshiba to get a tech dispatched.

Since the picture died slowly i suspect a capacitor on the powersupply board,if the screen flashes then goes black and sound is ok
could be the inverter board that drives the lamps.

Len..

tried to check first loose connection connector or cold soldered component parts like ic in the X board, which send signal at the screen panel display.if ok, look for the t-con board re seat the lvds cable connector.then if can not get with re seating the t-con board must have bad component parts.

the lamp has gone basicly there is a back light that lights the screen if this bulb goes you cannot see anything but it is all still there only way to fix this is to get a new lamp but sometimes the lamp is on a circuit board and the price is more then the tv is worth

Dark picture. I adjusted brightness, but it keeps getting dark. It has vertical lines that can be seen in grey areas on the screen.

remove the batteries for 2-3minuty, check if it works,
Enter the BIOS, set the boot order of devices on the 1-HDD, 2-CDROM

Either the backlight lamp or the invertor for it is failing. I suspect the colors and contrast isn't as it once was either. 

Fading typically is related to power supply heating or connection opening on the digital drive. You might try fan into vents just to prove this, or plug in outside in the cold, and see how long it is on in test mode.