Default galaxy s3 CM wont boot

i had CM with the installer app running (yeah i know, i'm not a smart man)
and wanted to update. started the package and the phone froze, so i rebootet it (with the menu option)

now all i get is the samsung galaxy s3 logo, i can't get into download and recovery AND idiot that i am i did not have debug mode
activated.

did i ruin my phone completely?
can anyone help?