Check that the universal charger has added points. If there is a multimeter, you can measure whether there is an output voltage, you can check whether the indicator light of the universal charge is bright. If the indicator light is on, and there is no voltage output at the output end, it means that your universal charger has \"struck\".
3. The next step is to check if your battery is good. You can take someone else's battery and see if it can be charged. If it can charge, then your charger is good. Then there's probably something wrong with your battery.
1, the polarity is not adjusted, that is, the positive and negative poles are reversed - you can switch the polarity switch or switch the positive and negative poles
2, battery aging - replace the new battery
3, universal charge failure - replace the new universal charge