Power "on", dark anthracite-black screen and not responding to any command

My six months old MacBookPro worked well until yesterday,

I shut it down, and some hours later after having stored it in my vault,

I could not reboot Yosemite OS X:

1. Electric Power "On" works - the MacBook apple-symbol is lighted, but

2. The MacBookPro shows a dark anthracite-black empty screen:

a) Nothing shows up on the anthracite-black screen and

b) The MacBookPro does NOT load Yosemite OS X,

c) Apple Diagnostics "D" does NOTwork - I tried it, several times with more then 7 minutes duration of pushing the D-button:
antharcite/black screen remains.

d) Erase and Reinstall = "cmd" + "R" both pushed for 8 minutes duration does NOT work:

antharcite/black screen remains.

WHAT ELSE can I do? - ℹ

-😐-