I agree with @Nikolay_Pro ... buzzing is a sign of a potential problem... either imminent or in the future. I would have been checking the inductors to see if any were cracked, or if pressure on any of them stopped it, and then given it a dose of epoxy to deaden the vibration or replaced it as the case may be.
If you're still interested in the schematic, here it is from the wiki information page for the rockpro64. Datasheets for all the major components are there also.
The fact that it powered down, and then stopped working actually sounds promising... sounds like something just isn't starting up again properly. The two LEDs(white/red) are both on the 3v3 rail as they are directly controlled by the RK3399, so unfortunately won't work unless the main CPU boots (and 3v3 present!), so don't tell you much more than that. Anyway, page 11 is a good place to start, and from the looks of it, if you check the RPi Header 5v and GND pins, that should always be present if the rockpro64 has power - looks to be the 'hardwired' system 5v, so check that first. If it's present, carry on to page 18, as it's probably one of the PMIC outputs that's gone.
If you're still interested in the schematic, here it is from the wiki information page for the rockpro64. Datasheets for all the major components are there also.
The fact that it powered down, and then stopped working actually sounds promising... sounds like something just isn't starting up again properly. The two LEDs(white/red) are both on the 3v3 rail as they are directly controlled by the RK3399, so unfortunately won't work unless the main CPU boots (and 3v3 present!), so don't tell you much more than that. Anyway, page 11 is a good place to start, and from the looks of it, if you check the RPi Header 5v and GND pins, that should always be present if the rockpro64 has power - looks to be the 'hardwired' system 5v, so check that first. If it's present, carry on to page 18, as it's probably one of the PMIC outputs that's gone.