I have a problem with my BBB. When connecting the power, the power led comes on, but no usr leds light up. If an ethernet cable is applied, the ethernet leds are on. I have tried holding down the uboot button when connecting and clicking the reset button as well as the power button. Should the power led turn off or flicker when either the power button or reset button is pressed? Because it doesn’t seem to.
Have you done anything recently to your BBB like flash a new Linux image, or modify any of the boot files ? I’ve experienced this myself when setting up various boot media and either making a typo, or misconfiguration in uEnv.txt.
If you can get a serial console hooked up to the board it may give you more insight into where it is failing during the boot process.
As for myself, the only compatible UART device I have is an MSP430 v1.5 launchpad. It works fine once the kernel starts loading, but since max baud is 9600 bps, it does not pick up uboot messages which I assume only works at 115200 bps.
Having a debug console adapter is definitely a plus, and is very useful in this case. But it is not impossible to troubleshoot problems of this nature if you know exactly what you’ve done.