If your ESCs have an Atmel MCU with a bootloader, you can reflash the ESC through the servo/signal cable using this USB Linker attached to a computer, the free driver below, and the free RapidFlash Chrome app
or free BLHeliSuite app
. This linker works with Atmel based ESCs. NOTE: When programming, detach positive lead from the signal (servo) wire then apply main power to the ESC. Lastly, connect from the app.