Q: My macbook pro 15'' 2012 screen remained white and flickering with some colours when i started it. . Please advice

Hello Diandra,

It may help to reset your Mac's SMC and PRAM.

Intel-based Macs: Resetting the System Management Controller (SMC)

http://support.apple.com/kb/HT3964

Reset your computer’s PRAM

http://support.apple.com/kb/HT1379

If the issue continues, the information detailed below can help restore functionality to your Mac's display.

 

1. If you're using an Apple notebook, confirm the AC power cable or adapter is securely connected to the computer and the cable providing power to the display is also secure. It is always good to have your notebook connected to AC power when an external display is in use.
2. Confirm display adapters are fully seated in their respective connections and that they are supported models and for the computer and display. Refer to these articles to assist you with adapter compatibility and further configuration information:
   • Monitor and Display Adapter Table
   • About Mini DisplayPort to HDMI adapters
   • Apple Mini DisplayPort adapters: Frequently asked questions (FAQ)
   • Thunderbolt ports and displays: Frequently asked questions (FAQ)
3. Remove all display cable extenders, KVM switches, or other like devices and retest to determine if the issue is resolved.
4. Try unplugging the video adapter or cable and then plug it back in.
5. If more than one video adapter is in use (or "daisy-chained"), troubleshoot by using only one adapter.
   • Example: A mini DisplayPort to DVI adapter connected to a DVI to HDMI adapter is an unsupported configuration because there is a series of adapters in use.
6. If available, try using a different display and or adapter (or use a different connector by using DVI instead of VGA, for instance).

Apple computers: Troubleshooting issues with video on internal or external displays
http://support.apple.com/en-us/HT201177

Cheers,

Allen