1) Loose connection of the Video Cable TO the motherboard, and/or TO the back of the LCD screen.
Can easily happen when reassembling.
(If you can't reuse the sticky tape on the back of the LCD screen, that holds the Video Cable to it, use more tape )
2) Incompatible LCD screen.
MATCH up the manufacturer's numbers on the back of the old LCD screen, to the new one.
They MUST crossover, and match up, if they are two different LCD screen manufacturers.
The screen Inverter is MATCHED to the LCD screen, also.
Matching up the Model Number, (Product Number for HP), may not be all the info you need.
Matching the numbers off of the old screen, for the new one, is.http://www.sparepartswarehouse.com/HP,Mini,1000,Laptop,LCDs-Displays.aspx
Under the red heading - Find Your Spare Parts - click on the blue Down Arrow to the right of the - Choose Model - box.
What Model is yours?
Write down the manufacturer and product ID number.
Now go to the far upper left of the page. In the box under - Part Number Search, type the letter/numbers for your old LCD screen.
On the page that comes up. Do they match?
Putting the letter/numbers in for the LCD screen you just purchased.
Do they match?
IF the old LCD screen works at all, reconnect it, and see if it works.
If so the LCD screen you purchased does not.
3) Make SURE the screen Inverter cables (Wires) are connected tightly.
[ Check the connection of the Video Cable to motherboard first.
Then the Inverters wires, then the Video Cable connection at the back of the LCD screen ]
An LCD screen cannot produce light. It needs an additional light source.
A Backlight is the additional light source.
A Backlight can be a CCFL or a series of LED lights
The HP Mini 1000 series of Netbook PC's uses a CCFL.
Cold Cathode Fluorescent Lamp.
Similar to Fluorescent lighting used in homes, and businesses, but on a MUCH smaller scale.
OR a series of LED lights. Depends on the model. (8.9 inch LCD screen models usually use CCFL. 10.1 models usually use LED lights)
A screen Inverter (FL Inverter) is used to convert power from the laptop, for the Backlight, and LCD screen.
Make sure there is 6 Volts DC power going through the Inverter.
90 PERCENT OF THE TIME the fault is the Inverter ]http://h10025.www1.hp.com/ewfrf/wc/manualCategory?cc=us&dlc=en&lang=en&lc=en&product=3832471&
HP Mini 1000 and Compaq Mini 700 - Maintenance and Service Guide
For additional questions please post in a Comment.