Hello,
I work at a service centre that repairs Sony LCD TVs and BenQ/Mitsubishi monitors. As others here have stated, it could be an inverter issue - but the problems you're experiencing points more toward a faulty panel (or specifically the CCFL tubes that reside within it)
In cases like yours, one of the CCFL tubes (or the high-tension wiring attached to it) becomes leaky. In the case of the wiring, part of the insulation fails and a corona (or in extreme cases, an ARC) forms around the damaged area and shorts to ground (via the rear of the LCD panel, as it's a grounded shield); The inverter/PSU powers up for two seconds, the display illuminates, but the control/logic realises too much current is being drawn by the inverter circuitry, and shuts down
In most cases it's a write-off, but if you've got the time, you can completely dismantle the panel itself, remove the CCFL tubes, and run them outside of the chasis to see if they remain lit...
Hope this helps!
