20 Most Recent Lenovo ThinkPad T420 Notebook Questions & Answers

The cmos battery is just under the keyboard. Release screw (1) of the keyboard is beside the ram slots underneath. So remove the ram cover first. Good luck!

Check your upgrades on the computer,or delete some of the unwanted junk or save them in the external HD.

Can you plug a monitor into the external Video connector, and do you see a display there? If you see a display on the external monitor, then the LCD is most likely bad.

Which test do you mean?

Try to restart the computer. Lenovo computers can be glitchy a lot, and restarting seems to help. If it's a touch screen, the computer can be "confused" on which mode of input you're using.

Keyboard Error

Is it problem accours in another monitor that pluged to your notebook? If no, the possibility is inverter failure. Try to replace the inverter to your service centre

There should be a function key to adjust the brightness at the top of your keyboard my laptop is F2 or F3 so at the bottom of the keyboard is a key label FN The Function key looks like a sun with an arrow if you are lucky to have it labelled. If this does not fix problem you may have a faulty laptop . There is a circuit called an inverter in your laptop that converts DC to a higher voltage AC to run the fluro backlight behind your laptop's LCD screen. If this inverter goes faulty you could experience the symptoms you are seeing. This would require a replacement of the inverter circuit board in your laptop by a repair service centre. http://www.youtube.com/watch?v=fSCJzA0EBo0 http://www.youtube.com/watch?v=2Yi6GNFcP3w http://ask.metafilter.com/92210/Backlight-or-Inverter-How-can-you-tell

The problem is probably at your TFT/LCD panel. Find to know by connecting your Notebook to another monitor is it dimming or not

you might find answers on lenovo forums

What version of windows are you running?Check out tutorials on youtube for you Windows version.

Try these steps might your computer is infected. Step Followed:- 1. Click on start and type Run. 2. In Run box type Temp. 3. Select all and delete all files. 4. Follow 1st step and type %temp% and then follow 3rd step. 5. Follow 1st step and type prefetch and then follow 3rd step. 6. Follow 1st step and type appwiz.cpl (add and remove programs) 7. Remove unwanted software and all antivirus . 8. Restart the computer. 9. Download Malwarebytes from "http://www.filehippo.com/download_malwarebytes_anti_malware/download/d7670bee6c8cd1bb9341d9a1ffbe832f/ " 10.Scan your computer and remove the infection. Thanks

BSOD = BLUE SCREEN OF DEATH This is mainly due to a driver issue, application error or worst hardware issue. Click below for more info.How To Fix Blue Screen of Death BSOD