Ready to move to Beta Site (my grandson's bed):
Attached the Arduino sketch and the connection drawing.
I used the existing structure of the faulty devide, took out the battery housing and put Arduino Uno instead + sd card reader. I used the existing buttons and motor.
I used 3.3 volt for the motor and the speaker, to have slow rotation and low volume.
To get louder - use 5v or add a transistor like for the motor.
The SD card has 3 great classics- Beethoven's "Ode To Joy", Handel's "Water Music" and Vivaldi's "Spring" , but one can change them easily - take out the SD, write the file you want instead of 1.wav,,2.wav or 3.wav. The files are converted from mp3 to 8bit 8Khz sampling rate wave files.