In order to complete the circuit, all wires must be touching the metal parts of each component. If your bulb doesn’t light up, check each side of the battery and the screws on the bulb holder to make sure the wires are in contact with metal.  Make sure screws are tightened down to maintain contact. In some cases, you may need to strip more of the insulation off the wire. Your bulb will not light if the filament is broken. Hold the bulb up to the light and ensure the filament is one connected piece. Try replacing the bulb with a new one. If the bulb isn’t the problem, proceed to the next troubleshooting step. If the battery is dead or low on charge, it might not have enough power to light the bulb. Using a battery tester, check the charge or just replace the battery with a new one. If this was the problem, your bulb should light immediately after replacing the battery.
تأكد أن كل الأسلاك موصلة بشكل سليم. تفقّد فتيل المصباح. اختبر شحن البطارية.