When turning my MacBook on, it loads about 75% and then turns off.

Have you tried to boot in to the recovery partition and run Disk Utility>First Aid?

https://support.apple.com/en-us/HT201314

Ciao.

First, if you haven't already and/or it's still possible, ensure that your data is backed up and recoverable.

Next, try resetting the NVRAM:

1. Completely shut down your computer.
2. Press the power button and then quickly press command + option + P + R
3. Hold those keys down until your computer reboots again and you here the startup chime.
4. Let go of the keys and let your computer reboot normally.

If this does not work, try booting your computer from Recovery.

1. Completely shut down your computer.
2. Press the power button while holding down command + R until the Apple logo appears.
3. After your computer finishes starting up, you should an OS X Utilities window.
4. Use the Disk Utility program to verify and repair connected drives.

At this point if the problem still persists, I would advise against further trouble shooting until your Genius Bar appointment. Zapping the PRAM and resetting the SMC multiple times will probably not help. It's possible your SSD is bad, and I've seen a number recommended solutions online that could actually make the problem worse by further degrading the SSD.

When you take your computer in they will likely run an MRI (Mac Resource Inspector), which is a fairly simple diagnostic test they will perform in front of you. A MacBook can pass this test with a bad SSD. If there is a problem booting into storage diagnostics after the MRI, the SSD is likely the culprit and will likely need replacement. Apple determined that certain 64GB and 128GB flash storage drives used in the previous generation of MacBook Air systems, sold between June 2012 through June 2013, have the potential to fail.

If not correctly addressed this problem can lead to a cycle of your computer functioning fine and then suddenly failing to boot, requiring you to wipe your HD and reinstall OS X every few months to get it working again. I hope this information helps, good luck.

First, if you haven't already and/or it's still possible, ensure that your data is backed up and recoverable.

Next, try resetting the NVRAM:

1. Completely shut down your computer.
2. Press the power button and then quickly press command + option + P + R
3. Hold those keys down until your computer reboots again and you here the startup chime.
4. Let go of the keys and let your computer reboot normally.

If this does not work, try booting your computer from Recovery.

1. Completely shut down your computer.
2. Press the power button while holding down command + R until the Apple logo appears.
3. After your computer finishes starting up, you should an OS X Utilities window.
4. Use the Disk Utility program to verify and repair connected drives.

At this point if the problem still persists, I would advise against further trouble shooting until your Genius Bar appointment. Zapping the PRAM and resetting the SMC multiple times will probably not help. It's possible your Flash Storage Drive is bad, and I've seen a number recommended solutions online that could actually make the problem worse by further degrading the SSD.

When you take your computer in they will likely run an MRI (Mac Resource Inspector), which is a fairly simple diagnostic test they will perform in front of you. A MacBook can pass this test with a bad SSD. If there is a problem booting into storage diagnostics after the MRI, the SSD is likely the culprit and will likely need replacement. Apple determined that certain 64GB and 128GB flash storage drives used in the previous generation of MacBook Air systems, sold between June 2012 through June 2013, have the potential to fail.

If not correctly addressed this problem can lead to a cycle of your computer functioning fine and then suddenly failing to boot, requiring you to wipe your HD and reinstall OS X every few months to get it working again. I hope this information helps, good luck.