This code "const PROGMEM char bootNotice[]" means array of char, usually assigned with either of:
const char msg1[] = {'a','b','c','\0'};
const char msg2[] = "abc";
Both the above will yield the same output. Your code is simply wrong becuase you are declaring an array of char and assigning an array of cstring which may yield an unpredicatable result.
"What for the bootNotice[], that problem seemes to have gone by now" - Oh boy, bugs fixing them selves are scary critters..