Error Compiling Rumba + 12846 Full Graphic in Arduino 1.8.5

Hello Community, as absolute newbi i like to ask for help concerning a - for me - unsolvable problem.

Rumba board found on com4 Display 12846 full graphic from rep rap discount Marlin 1.1 Arduino 1.8.5 u8g2lib added to library

Problem is that compiling stops with the message:

Error compiling for board Arduino/Genuino Mega or Mega 2560 exit status 1 Error compiling for board Arduino/Genuino Mega or Mega 2560

I tried "everything" that i read here so far like restarting Arduino, reinstalling the u8g2lib.zip with the Arduino IDE, restarting the computer ,....

If someone here could please have a look over my code and suggest changes etc. would be really great and i like to thank in advance for the effort.

MFG, Joe (the helpless one) lol

When you encounter an error you’ll see a button on the right side of the orange bar “Copy error messages”. Click that button. Paste the error in a message here USING CODE TAGS (</> button on the toolbar).

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Rumba board found on com4

So wtf is one of those? Does it contain a Mega 2560 processor? If not you have chosen the wrong processor from the tools menu.