Did you diagnose first?
1) First thing to check is to make sure the graphics chipset is OK.
[Chip and Chipset are slang terms for I.C.
The I.C. for graphics is the graphics chipset, or more properly, the G.P.U.
Graphics Processing Unit,http://en.wikipedia.org/wiki/GPU
A) Laptop OFF, monitor OFF, connect a VGA monitor to the blue VGA port, on the left side of the laptop.
You can use a CRT type of monitor (Looks like a small TV), or a flat LCD screen monitor if it has a VGA Cable,http://en.wikipedia.org/wiki/VGA_connector
(Scroll down a little bit for example of VGA Cable)
B) Turn the monitor on. If a CRT type allow it to warm up a couple of minutes.
Turn the laptop on.
No display on external VGA monitor?
Hold the Fn key down, and tap once on the F8 key.
(The F8 key is the Display Toggle-Over key)
Still no? Hold the Fn key down again, and tap once more on the F8 key.
[There are at least 3 display options available;
1) Internal monitor of laptop ONLY
2) Internal monitor of laptop AND external VGA monitor
3) External VGA monitor ONLY ]
Good display on external VGA monitor = good graphics chipset.
The problem is the Video Cable, or in the Display Assembly.
An LCD screen does not produce light. It needs an additional light source.
A Backlight is the additional light source.
A Backlight can be a CCFL, (Or two of them), or a series of LED's.
(Light Emitting Diode)
A CCFL is a Cold Cathode Fluorescent Lamp.
Similar to Fluorescent lighting used in homes, and businesses, but on a MUCH smaller scale.
Average thickness is 2mm. That is a little larger than 1/16th of an Inch.
Average length is almost as long, as the LCD screen is in height.
The Packard Bell Easynote TJ65 uses LED backlighting.
A screen Inverter is used to convert the power (Electricity), from the laptop; for the LCD screen, and Backlight.
LED backlighting does not use a screen Inverter.http://www.laptopscreen.com/Spanish/model/Packard%20Bell/EASYNOTE%20TJ65/
You are down to the Video Cable, since you have installed a new LCD screen.
The Video Cable connects to the motherboard either under an area, under the Keyboard; or under the Switch Cover.
It then leads across the motherboard, and through the left Hinge.
From there the Video Cable leads into the Display Assembly, and connects to the LCD screen, and LED backlighting.
Due to just normal repeated opening, and closing of the laptop; the Video Cable connections TO motherboard, and/or TO back of LCD screen; may become loose.
Connection at motherboard side needs to be physically checked; to ensure this connection is not the problem.
You also may not have made a good connection to the back of the LCD screen.
(And it would be logical to also check the LED cable connection, while you are at it. Even though a bad LED connection would cause a dark screen, and not a White one)
Also the Video Cable's sheath should be visually checked for obvious signs of damage.
Any apparent signs of damage to the sheath of the Video Cable; may also mean damage to the tiny wires inside the cable.
In your situation you need to know for SURE, if the Video Cable is good. Video Cable should be removed, and a multimeter set to OHM's is used, to check continuity of every wire in the Video Cable.
An economical multimeter is around $5 to $12, if you do not have one. Or take to a small computer shop, and have it checked for a few bucks.
Video Cable checks out for continuity, and connections are Tight; you have a bad new LCD screen, or the wrong one.
For additional questions please post in a Comment.