Only recently purchased a 2007 CBR125r (my first bike). Its in great condition and had been running very smooth until this morning. I went to start it up for work as usual, ignition light - OK, starter cranked - OK, and it fired up for a few seconds but the idle was pretty low so I gave it a bit of throttle to get it going and it cut out!
When I went to start it again I wasn't getting anything, no lights, no crank, just a strange electrical whining sound coming from the tail/battery area. Even when I had the engine kill switch on (which technically should cut the battery - right?) it still made a whining sound when the ignition was set to on - albeit not as high pitched.
Tried to push start it and it kinda sounded like it was cranking, but something still sounded off and it didn't fire up. My initial thoughts are battery, but that noise is really off-putting. Anyone else experienced this?

 

If you don't have any lights, it's most likely the battery or main fuse. I don't have a wiring diagram for that bike so I can't tell you where to look for it. On most bikes the main fuse is on the Starter Relay near the battery.