White screen when you start the laptop, and then when you connect an external VGA monitor, you can only operate in Safe Mode?
Or white screen except when you are Safe Mode?
Doesn't matter anyway, just wanted to see what you are stating.
1) Have you connected an external VGA monitor to the laptop, and seen if you get a good display on the external VGA monitor?
No display on external monitor?
You have at least 3 display options available;
A) Internal monitor of laptop ONLY
B) Internal monitor of laptop AND external VGA monitor.
C) External VGA monitor ONLY
Hold the Fn key down, and tap once on the F5 key.
(The F5 key is the Display Toggle-Over key)
Hold the Fn key down again, and tap once more on the F5 key.
Good display on external VGA monitor?
Problem is the Video Cable, or inside the Display Assembly.
White screen on external VGA monitor also?
Problem is the graphics chipset.
[Actually it is probably inadequate cooling for the graphics chipset, and this makes a bad contact of graphics chipset TO motherboard. If this is found to be the problem I can explain further, and in much more detail ]
Inside the Display Assembly:
A) Screen Inverter if it is CCFL backlighting.
May or may NOT be a screen Inverter if it uses LED backlighting.
[ CCFL - Cold Cathode Fluorescent Lamp
LED - Light Emitting Diode ]
B) LCD screen.
The Video Cable connects to the motherboard, in an area either under the Keyboard, or under the Switch Cover, or bottom of the laptop.
Goes by many names. It is the strip of plastic above the Keyboard, and below the LCD screen. Usually has the Power On button, and LED indicator lights; plus speakers, sometimes ]
From there the Video Cable goes under the left Hinge, and up into the Display Assembly.
If a screen Inverter is used, a small cable comes from the main cable, and plugs into the screen Inverter.
The main cable connects to the back of the LCD screen.
Due to normal repeated opening, and closing of the laptop; the Video Cable may be pulled on.
This can create a bad connection on motherboard side, and/or screen Inverter cable connection, (IF used), or to the back of the LCD screen.
It can also cause damage to the Video Cable.
Once you post the product number I can guide you step by step, show you the components I'm talking about, and track down a Service Manual link, and possibly pictorial disassembly information.
The Video Cable connections are checked first.
A loose connection can cause what you are seeing.
The sheath of the Video Cable is also scrutinized for damage.
Obvious damage to the sheath, may mean damage to the tiny wires inside the Video Cable.
Another thing that can cause what you are seeing.
Video Cable connections prove not to be the problem, then the Video Cable is to be removed, and a continuity test performed on it.
Multimeter set to OHM's. (1K)
If a multimeter is not at your access, then suggest taking the Video Cable down to the nearest small computer shop, and have the resident tech check it for continuity. Should only be a couple of bucks.
YOU MUST rule out the Video Cable as the problem, before going on.
Video Cable checks out?
Then if a screen Inverter is used, this is the next component in the diagnostic flowchart.
Problem is this; it requires a sensitive multimeter to test a screen Inverter. Think fairly expensive,http://www.fonerbooks.com/test.htm
The plastic frame in front of the LCD screen, is the Display Bezel.
The screen Inverter is located behind the Display Bezel, and mounted down towards the bottom of the LCD Screen Frame.
Due to the multimeter issue, the above noted ease of accessing to replace, and the usually low cost of the screen Inverter; most decide to just replace.
Screen Inverter replaced? Same problem?
The problem is the LCD screen.
No screen Inverter used? The problem is the LCD screen.
Video Cable; Usually around $9 to $20
Screen Inverter; Same.
LCD Screen; from $70 to $240. Just depends on what Lenovo laptop we're talking about here.
This is why you diagnose first.
Would be foolish to assume the problem is the LCD screen, and purchase one; when the problem may have just been a loose Video Cable connection, or one of the $9 to $20 components stated above.
Ready to diagnose?
Post the Product Number back in a Comment.