How to go to boot options? I have a MacBookPro Retina 13" early 2015 and I can not enter the boot options.
The Device is running OS X El Capitan.

I have tried the following things with no luck:

Attempt 1 - Hold the Option


Restart
press and hold left option right after hearing the chime


Result: Black Screen, I need to press and hold the power key to make the device boot.

I have also tried this with an external keyboard with the same result.

Attempt 2 - SMC Reset


Restart
Reset the System Management Controller by pressing and holding option+command+R+P right after the chime, until the next chime.
Retry Attempt 1


Result: Same as Attempt 1.

Any ideas what I could do?
⌥ alt/option should be held right after pressing the power button including during the boot chime until Startup Manager is shown (https://support.apple.com/kb/HT202796). Holding the key only once the chime has happened may be too late.