first try replace cmos battery with a brand new one and clear cmos settings by reset RTCRST jumper on motherboard. 
Hi! My Optiplex 7010 is blinking in the 2,3 pattern after it fell over. I tried almost everything but still does not startup. Does anyone know how to fix this? On the manual, it says "system board, memory or CPU failure" Thanks.
Optiplex 7010 amber light blinks 2,3