User Manual:
XT60+XT30 2-in-1 Usage:
The red LED light being on indicates normal operation; if the red LED turns off, it means a short circuit has occurred and the fuse has tripped.
To reset the short-circuit detector, unplug the connector for 10 seconds.

The JHEMCU Smoke Stopper prevents potential disasters. It is a self-resetting/resettable fuse installed on the power line leading to your quadcopter.
When you power on your drone for the first time, it is commonly known as a “smoke test”. If everything works, you pass; if not, you’ll see blue smoke and need to replace parts! With the JHEMCU Smoke Stopper, you won’t have to worry about this anymore. The JHEMCU Smoke Stopper is different! Compared with standard smoke stoppers, the JHEMCU Smoke Stopper has much lower trip current and hold current, and faster response time. We also offer more input voltage options and more input/output connectors than any other smoke stopper.