Adapter Voltage of Laptop

[Flashbear]

I am repairing an Acer Aspire One Happy,
The Problem is, when i turn on the the unit, I see no images.
But when i watch is closely with a Lamp, I can see the desktop images and letters. what can cause this problem? do I have to change the LCD screen?
and here's one thing. When I read the voltage of the power adapter, it has

output : 19 V , 2.15A
Input : 100-200V~1.2A, 50-60Hz

then the battery power is
11.1V, 2.12Ah

is that making the Problem?
thank you vey much.

 

[digitaldoc]

The backlight of the monitor has gone out. This can be due to the bulb directly dying, or the inverter that supplies power to it no longer working. Below I linked to a guide on how to deal with this.

http/www.dnd.utwente.nl/~grit/backlight/ccft.html