Use this Gristleism check list
1 - Have you inserted fresh batteries?
2 - Are the batteries inserted correctly? - please check the orientation diagram in the battery compartment
3 - Have you turned-on the unit using the left-hand control? - which is a combined on/off switch & volume
4 - Also please try turning the right-hand (pitch) control to the rightmost/maximum position.
If none of these tips help then we must assume your Gristleism is DOA.
If so please contact your retailer for a replacement.