Describe the installed lighting arrangement
Look at the product information rather than opening the motor housing. Record whether the light fails at every command, only with motion activation or only from the wall control. If the garage has multiple openers, identify the affected unit clearly. A normal door cycle does not tell the technician which lamp or lighting control needs attention.
Keep diagnosis specific to the model
Some integrated LED systems use components that differ from an ordinary screw-in lamp. Chamberlain Group publishes separate instructions for those assemblies. Do not order a generic bulb for a sealed light module or assume an internal repair is a safe homeowner task. Electrical housing access, wiring and battery isolation should follow the relevant instructions and an appropriate service assessment.
Separate repair from improved room lighting
Explain whether the aim is to restore the opener lamp or provide more light throughout the garage. A larger workshop or storage area may need independent lighting that is not part of the door operator. Ask which repair is proposed and whether the existing light settings will be retained. Use a separate safe light source while the fault is unresolved.
Your questions
Does the light failing mean the entire motor is worn out?
Not by itself. Lighting components, controls and the operator’s drive functions should be distinguished during diagnosis.
Can a backup battery mean the housing still has power after unplugging?
A unit may have more than one power source. Do not open it based only on removing the wall plug; follow model-specific service guidance.