"The backpack is open, you are going to drop everything."
Translation:Ryggsekken er åpen; du kommer til å miste alt.
"Sekken" should also be considered correct, even if "ryggsekken" is more precise.
The comma turns into a semicolon? I know I don't have a full grasp over grammar yet, so what is the problem with "Ryggsekken er åpen, kommer du til å miste alt."?
Actually, the comma in the English version is grammatically incorrect; they should both use a semicolon (like so). There's a name for using commas in this way, but I can't remember what it is. Usually it's only acceptable in informal communication, like texting. Using a comma like that in an essay would get you marked down.
I think the problem with your sentence isn't the punctuation, but the fact you wrote 'kommer du' instead of 'du kommer'. You'd write 'kommer du' if it were a question i.e. 'Kommer du til å miste alt?' ('Are you going to drop everything?').