One word is immotile:

[Merriam-Webster]

: lacking motility

a free-form sculpture that manages to suggest movement while remaining an immotile object

(In contrast, motile means "exhibiting or capable of movement.")

However, I can think of no word that only means incapable of initiating movement—as well as never having been capable of movement in the past.

A battery-operated toy, for instance, can move. Once its battery dies, it is now motionless, immotile, and inanimate. But if the battery is replaced, movement is possible again . . .

One word is immotile:

[Merriam-Webster]

: lacking motility

a free-form sculpture that manages to suggest movement while remaining an immotile object

(In contrast, motile means "exhibiting or capable of movement.")

However, I can think of no word that only means incapable of initiating movement—as well as never having been capable of movement in the past.

A battery-operated toy, for instance, can move. Once its battery dies, it is now motionless, immotile, and inanimate. But if the battery is replaced, movement is possible again . . .