Stock front blinkers have three wires. Ground (Black), running light (Blue) and blinker (chocolate).
I can recall reading where a few folks have managed to let the wires touch and blown fuses as a result. Shouldn't be an issue if the key is turned off. Although, best practices would say disconnect the battery before you do anything.
Edit: you didn't mention if the back blinkers were already LEDs. The reason I'm brining it up is that sometimes the blinkers will not work when you replace all the stock ones with LEDs. For some, even one set of blinkers causes issues (fast blink or no blink). The normal fix is to get a different blinker relay.