The ET1 is a discontinued product.
The interface description for management tasks like silent app install was not publicly released. It was intended to be used by MDM tools primarily.
There is no root access either.
As Andreas wrote, ET1 is actively developed anymore. It never got support from our StageNow or EMDK tools but we had some standalone utilities that could be used for those activities you asked for.
please contact our support organization in Brno to get more information: email@example.com
Or contact the Turkish support center:
+90 212 314 1032