BBB power led blinks and device starts after pressing power button


I’m working with a Beaglebone Black with a Debian distribution installed. When I power the board, the power led blinks and the device usually doesn’t turn on. However, if I press the power button several times it starts, but not always at the same time and just blinking the led at the rest of them. I’m using a power supply of 5V 2A. I don’t know if it’s a power issue or any other thing.