First time on the Raspberry Pi family, I just unboxed my Pi 3 model B with two successful boots after installing Raspbian.
Later I tried to boot again and I got a yellow flash symbol at the left side of the monitor during and after booting, and the power red led light keeps blinking. The mouse and keyboard are not responding, and there's no power on the USB port. I checked the ethernet port and no problem.
My power supply is 5V 2A. I also checked GPIO pins 2 and 6, and they are at 5.28V. Seems there is enough power but what could be the problem?