Fix OS-X white screen issue while booting

When booting OS-X machine sometimes you may face following kind of issues.
- Stuck in white screen
- Stuck in blue screen
One of the following options would help you to overcome these issues.
1. Boot safe mode
Press SHIFT key and on power button. This command will boot the machine in safe mode.(it will take some time)
SHIFT 2. Boot recovery mode
Press CMD + R buttons and on power button. This command will go to mac disk utility window which you can do recovery, reinstall os etc
CMD + R3. Boot internet recovery mode
Press CMD + ALT + R buttons and on power button. This command will helps when your recovery partition is broken(if it broken you cannot directly go to disk utility). Booting with this command will start to download recovery partition and disk utility. After download you can go to disk utility.
CMD + ALT + R4. Reset NVRAM and boot
Press CMD + ALT + P + R buttons and on power button. This will reset nonvolatile random-access memory on your computer. NVRAM stores settings such as,
- Sound volume
- Display resolution
- Startup-disk selection
- Time zone
- Kernel panic logs
- etc
Resetting NVRAM would helps you to solve the white screen issue
CMD + ALT + P + R5. Choose startup disk
Press ALT button and on power button. This command will navigate you to select the startup disk. If startup disk not selected in the computer this command will helps you.
ALT