How about "Das Gerät ist es nicht"???
I don't understand why in a previous exercise "Moebel mag er nicht" is the right form (as opposed to "Er mag Moebel nicht") and at the same time, in this exercise, "Es ist nicht das Gerat" is the only correct answer.
If you wanted to say "It is not a device," then "not a" becomes "kein." However, the sentence says, "It is not the device."" Since you want the sentence to include the article "the" (das), you must use nicht.