Is the noun "device" correctly used as a modifier in the phrase "the device box"?
Solution 1:
Yes it is correct to use nouns to modify other nouns as premodifiers since they express either some sort of descriptive meaning { only adjectives called describers } or some kind of classification { adjectives or nouns called classifiers }. For example:
The ancient town , aggressive driving, some trite-but-true thing....> ( describers (adjectives) give some attributes or qualities about the head words)
a Christmas carol , the cherry trees, to refine test drive, ... or ... wooden slat , western songs....> ( nouns and adjectives as classifiers which category or classify the head words).
But in your case The instruction manual can be found in the device's box the noun device doesn't modify ( classify or describe) the noun box. The 's genitive expresses a possession between the box and the device ( the driver's name, Dunken's book,,,,,etc). It plays a role as possessive determiner that points to the entity which the head word is referencing. So The device's box is correct and you can also say The instruction manual can be found in the box of the device
Solution 2:
An attributive noun is a noun that modifies another noun like an adjective. However...
No, in your example you cannot use "device" to modify "box." The reason you need to use the possessive is that the instructions are for the device, not the box, but they're not in the device. They're in the device's box.
To further demonstrate this, an alternative way to structure your sentence is:
The instruction manual for this device is inside its box.