i've done multiples attempts, following this steps (https://support.apple.com/en-us/HT204063) and my macbook still doesn´t start and ends up appearing the folder with a flashing question mark. why isn´t it working?
Refer to If your Mac starts up to a question mark - Apple Support.
Since Reset NVRAM or PRAM on your Mac - Apple Support isn't working, continue under If the question mark persists, follow these steps:
and, after i stopped pressing the four keys (for around 20 seconds and after the second startup sound), after some seconds a third startup sound appears.
folder with a flashing question mark and unsuccessful reset NVRAM
