Speedometer display problem
 

I have a 2009 KLX250S I just bought. The guy I bought it from said the speedometer doesn’t work, but the indicators for neutral, lights, turn signals work. Then today I start it up and the display lights up but isn’t showing anything on the screen. Is there something I should be looking for that might fix it before I get a new speedometer.

Sounds weird but check that your battery is actually good. A battery that is failing to hold a proper charge can start the bike but not have enough juice to properly run the dash.
Try charging the battery. If your dash suddenly works for a bit and then starts blinking, it's the battery.

i second that

Go to page 16-66 in the service manual and do the diagnostic test.