Leave it off rather than asking the motor to start against a tightly packed load. The safe next step depends on the model's documented owner procedure and the material that was added.
What the observation tells you
A full chamber can conceal hard objects, fibrous waste or packaging. Pushing the load down further removes useful information and may worsen an obstruction. Never put a hand into the disposer, even when it appears silent.
A useful next step
Safely isolate it and explain what was loaded when seeking advice. If the manufacturer does not provide a suitable owner method, let an engineer clear and inspect it before normal use resumes.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.