The level of overclock you can apply on several RPI3 may be different from one to one, depending on tolerance of the chipsets and luck. For example mine (RPI3) brick at the max level of overclock but is OK at the penultimate level. Some may brick earlier.
You can avoid to reflash the OS by editing the config.txt file into the /boot partition of the SD card and erasing the lines concerning overclock. If you boot successfully, go back to the overclock menu in ES and put it back to no-overclock (ES keep the info although no overclock is applied).
Remember to have a good cooling and a good power supply when you play with overclock .