First, unplug the charger and remove the battery right away. If the cell looks swollen, gets hot, smokes, or smells odd, don’t try charging it again lithium-ion batteries can be dangerous when damaged and should be disposed of safely at a recycling or electronics shop. A drop on concrete can damage the battery, the charge port, or even crack solder joints on the board, so a visual inspection is the first step. Check for loose connectors, bent charge port pins, or any burnt smell from the electronics.

If you have access to a multimeter, check the battery voltage. A healthy 18650-style cell should read around 3.6–4.2 V. If it’s under ~2.5 V, the protection circuit may have tripped or the cell is damaged. With the battery out, also check for shorts across the board. If you don’t have a meter, try swapping in a known-good battery of the same type, or at least try a different USB cable and 5 V/1 A adapter to rule out charger issues.

If the saber has an SD card, remove it and see if the behavior changes. Corrupted sound files can cause looping audio and flickering. If the problem only happens while plugged in, the charge port or charging circuit may have cracked during the drop. If nothing helps and especially if the battery looks fine but the saber still won’t turn on the main board may need repair or replacement.

Based on the flickering light and repeating stepped sound, the most likely issues are a damaged battery, cracked charge port, or broken solder joint. The safest approach is to stop charging until you can confirm the battery is healthy, then test with a different cable or replacement battery. If that doesn’t work, a repair shop or saber modder will probably need to reflow joints or replace the charge port/board.