There can be a host of reasons why your light is not charging. Here are some techniques to help you troubleshoot.
1. Try a different power source. If you charge through your computer/laptop try using a 2 amp wall socket charger to confirm that it is not a USB port issue. A computer's USB port is usually only active when the computer is on (not hibernating) and many times don't provide adequate amperage to begin with. There are also many knock-off wall adapters you can find online and at the checkout lines of grocery stores that either don't provide enough current or break after a short period of time. Be sure to use a trusted brand for best results. Lastly, even though it may seem unnecessary, try a different wall socket all together. You could be unaware that a fuse is blown in your house or there is an underlying wiring issue with that particular outlet you are using.
Urban light charge indicators are known to blink green and red if the current is not sufficient. The light will also simultaneously enter Travel Lock-out mode if the light is plugged into an outlet or computer with amperage below .5amps.
Taz lights can actually tell you what amperage your computer or outlet is giving you. Holding the secondary button while the light is plugged in will indicate the rate at which the Taz is charging:
Red: <0.5 Amp
Amber: 0.5-1 Amp
Green: >1 Amp
2. Try a different charge cord. Charge cords are perhaps more abused than lights--they get bent up, tangled, and tossed around carelessly. This abuse is expected, but sometimes the cords received trauma that they weren't intended to endure. It hard to recognize whether or not if the cord is damaged, so don't be hasty to rule this option out.
Our cords are standard Micro-USB, a common style for many of today's rechargeable electronics. We use a particular length of 18"; short enough to deliver the amperage needed to charge the light efficiently and long enough to make it practical for everyday use. We recommend using a cord around the same length but it doesn't hurt to try what you have on hand, regardless of length, before finding other means.
*Cords over 4 feet will likely not provide enough amperage to the light.
3. External batteries. The Smart External Battery Charger is the only current charger for all Seca and Imjin [Stella] products. This replaced the Multi-Chemical Charger from past generations of lights. First step is to try a different wall outlet or power strip. Check to see if there are any wires pulling loose from the base of the plug. Red or white wire sheaths where the cord is connected to the plug will be exposed (time to replace the charger). If you also have other batteries or chargers from previous Light & Motion purchases, try different combinations to nail down whether you have a battery or charger issue.
The green light on the charger, indicating a full charge on either the Smart External Battery Charger or the Multi-Chemical Charger will illuminate within the first 10 minutes if the battery has expired. This usually happens after a battery has been kept in storage for years, or has reached its end-of-life around 3-5 years of consistent use.