How to solve the oc boot card machreboot

1, check whether there is a problem with the hardware. For example, check whether RAM, hard disk, keyboard and power supply are working properly.

2. Check whether the startup sequence is correct. When starting, you should choose the correct startup sequence, such as USB, hard disk or other startup options.

3. Try to reset the system settings. You can check and repair disk problems by pressing the Command+R key at startup, and then selecting Disk Utility.