Thermal shock/cycling does indeed reduce the life of both the backlight and the inverter, so anything you do to reduce the number and severity of the thermal cycles will make those components last longer.
...this says to me is that the screen (for this particular laptop) draws most of the power.
That is true, the screen is by far the most power hungry device in a modern laptop, accounting for more than 40% of the total power draw
in most systems.
...I'm curious to know how difficult it is to replace the inverter. Is it something built into the motherboard? I've heard they are sometimes built into part of the display.
Inverters are usually mounted somewhere in the LCD panel (usually at the base of the lid in a laptop), and are specific to the LCD used
While they are somewhat failure prone
, fortunately they are easy to find
, relatively inexpensive, and easy to replace
. Because they are a failure-prone component, they seem to be available long after a given laptop has been discontinued.
Note that newer laptops use LED backlights that don't use an inverter and have a significantly longer life than CCFL backlights, plus they also consume about 10% less power