Ibm sreen shows but very dim, both on battery and when plugged to

If it's a windows 10 laptop right click on the desktop and go to display setting and increase the brightness.

Most laptops have special key legends (in blue) on the Function Keys and a few others. One of these keys will have a legend that shows a "bright sun", one that shows a "dim sun" . There is a "FN" key, usually to the left of the spacebar. Press this key and the "bright sun" function key at the same time to increase brightness. Successive presses will increase until max brightness is reached.

go to start-->control panel--->display--->adjust brightness

i need to know what operating system you use this will work for only Vista and 7 and 8 and 8.1

Occasionally, you may find your laptop's monitor is too dim for your liking. A normal desktop computer's monitor has an on-board menu system that lets you adjust the brightness and picture control settings as you please. A laptop monitor has no such controls. You can adjust the brightness of your laptop monitor using your laptop's keyboard.

1.Press and hold the "FN" key on your laptop's keyboard. This is the "Function" key, which operates much the same way that the "Shift" key does: It allows keyboard buttons to be used for multiple purposes. It's located in the lower left corner of most laptop keyboards, next to the "Windows," "CTRL" and "ALT" keys.
2.Look at the top row of keys on your keyboard for a key with a tiny triangle pointing upwards and the symbol of a sun on it. This is the "Increase Brightness" key. With the "FN" key held down, press the "Increase Brightness" key. On most laptop keyboards this is the "F7" key, but it varies depending on the model.
3.Continue to hold down the "FN" and "Increase Brightness" key until your dim laptop monitor has reached the level of brightness you require. A laptop monitor can only get so bright. It will stop at its highest setting.
4.Release the "FN" and "Increase Brightness" keys. You have now fixed your dim laptop monitor.

I hope you find it very helpful.

Examine the keyboard. There should be a symbol on most of the function keys (F1, F2, etc.). Look for one that looks like a sun or lightbulb, either with an arrow pointing up or with the sun/lighbulb filled in. Hold the 'Fn' key, and tap the up/bright sun/lightbulb key a few times. The screen should increase in brightness.

If you cannot find the specified keys, you may be able to adjust brightness from inside Windows. Right click on the battery icon in the taskbar and open 'power options'. Look for a sun and moon with a sliding bar between them. You might also be able to adjust brightness by customizing your desktop (right click on the desktop and look for the proper menu).

go into your bios at start up press f2,del or f8 and you'll see some kind of brightness control pretty sure but their is several thinkpads

it is done to save power from the battery.
what you can do is to click on Function + <up arrow> key and it will increase the light.
also you can check the power setting:
1. right click on your desktop and go to properties
2. go to Screen Saver
3. click on Power
4. check the settings under "Battery"

Right click on the battery icon in the taskbar, go to Power Options or something similiar. Change the plan settings for the power plan you're currently in. Check the brightness ratio for both battery and plugged in mode. This problem might come if you or someone had tinkered with the settings.

It could either be your power settings dimming it (battery saver mode), or more likely when you replaced the screen, you replaced the backlight with the one that came with it. The replacement backlight is probably not as good as the one you had. You can try putting your other backlight in it (the backlight is that circuit board near the hinge that you plug in when you switch the screens out). Since it's going in and out, I'd check the power settings first though.

One of 2 things happened....
1) You Blew the Power Inverter... The Power inverter is a thin rectangular circuit board that plugs into the display panel cable and also powers the LCD Bulb.. If This Part Fails - You Lose Light to the Display even though the display will still be on and viewable against a bright light....

2) The LCD Bulb is Faulty... When the LCD Bulb Fails it will typically give pre-warning signs- though not always.... It will give signs like the whole screen has a light orange or pinkish tone to it, but eventually it will blow and no light at all to the Display Panel....

Both Of These Are Repairable....

The Power Inverter Can Be Purchased Off of Ebay, For Around $15 to $30

The LCD Bulb Itself is also Replaceable.. Though It is a Job Only to Be Performed By An Experienced Laptop Tech... Bulbs as well can be bought off of ebay for a few bucks..