Hi @Milad_Mafi ,
finished my setup for both Levels now and found two little mistakes.
In Homework of Session 4 - Level 2 in the Material assignment for the battery you wrote volumeOnGeoVolumes_0 in the text but its volumeOnGeoVolumes_1 in the picture. Might be a little bit confusing for some guys here. Got an error at the end for assigning two materials on one component but found the mistake fast 
The second one is also in Homework of Session 4 - Level 2 at the point where we define the acceleration of the Arm right lower point acceleration. Component selection: y displacement is wrong it is more likely Component selection: y acceleration.
But these are just peanuts. 
Cheers,
Jousef