The motor may be fine even if the drum does not move.
Start Here
Try turning the drum by hand with power off.
Inspect belt where accessible.
Check door switch behavior.
Listen for motor hum.
Look for seized rollers or idler parts.
A useful diagnosis turns a vague complaint into a smaller technical question. The motor may be fine even if the drum does not move. For dryer will not tumble, concentrate on heat, drum movement and unrestricted airflow. Use every working function as evidence: if one stage still behaves normally, that fact eliminates causes that would have stopped the appliance earlier in the sequence.
Observe the timing before touching anything. Note what happens immediately after Start, what changes just before the fault, and what remains normal afterward. Lights, relay clicks, water movement, motor or fan sounds, heat, vibration and error codes are useful only when tied to a point in the cycle. A fault that appears instantly is a different problem from one that appears only after the machine warms up or reaches a later stage.
Begin with the cheapest conditions to verify: try turning the drum by hand with power off, then inspect belt where accessible. Do not merely glance at them. Compare the actual condition with the manual, correct anything obviously wrong, and retest before moving deeper. Simple installation, maintenance and user-setting problems regularly imitate failed electrical parts.
If those checks pass, move to check door switch behavior. Then decide whether listen for motor hum can be evaluated safely with power isolated. Choose one test that answers one question: blocked or clear, open or closed, free or jammed, intact or electrically open. If a test result would not change your next decision, the test is probably not worth doing.
Avoid running a motor against a jam, reaching into a powered cabinet, and assuming a broken belt is the only cause. All three skip evidence and can turn a minor fault into an expensive one. After a correction, reassemble guards and connectors, restore normal settings, and reproduce the original operating conditions. A single successful start is not proof; the original symptom must stay gone through the stage that used to fail.
A Safe Step-by-Step Check
Document the exact symptom and pay special attention to try turning the drum by hand with power off.
Remove external causes first; specifically verify inspect belt where accessible.
With power isolated where required, inspect check door switch behavior and then evaluate listen for motor hum only if it can be done safely.
Reassemble fully and run a controlled test under the conditions that previously caused the fault.
Common Beginner Mistakes
Running a motor against a jam.
Reaching into a powered cabinet.
Assuming a broken belt is the only cause.
STOP AND GET HELP: If the next useful test requires exposed live mains, defeating a safety interlock, opening a sealed refrigeration circuit, disturbing gas controls, or entering a microwave high-voltage section, the diagnosis has reached the professional-service boundary.