There is no blinking LED update for this phone on stock ROM.
If it blinks alternating orange and green (or green and orange for that matter) your phone is overheated and should be allowed to cool before any more attempt at recharging. This might also indicate that your battery is shot.
It can overheat by running lots of data over wifi, or other cpu-intensive tasks on low battery such that the battery is constantly charging/discharging trying to keep up with the demand. The battery can cook itself into deterioration after too much usage/heat, and may be swollen in the middle. If it is swollen in the middle, you can probably stop right now and test the phone with a different battery. Even if not swollen, the battery could be too old to work properly any longer.
If not swollen, you can remove the battery and let the phone and battery sit for 30 minutes in a cool place to allow them to cool, then re-insert the battery and attach the charger cable, but do not turn the phone on. Observe if the flashing orange/green begins again, and if so, I'd recommend trying a different battery/charger, as something is shot--most probably the battery or charger. If it flashes solely orange, the battery is completely dead/discharged--see if it goes solid orange after 30 minutes. Do not turn the phone on while doing this, so you can make the determination without other factors interfering. If it goes solid orange within 30 minutes, continue on to see if it goes green after maybe 4 hours, and if so, I think it's a safe bet the battery and charger are working, and it would be safe to turn it on and observe what happens then. If it doesn't go solid green within 4 hours but is solid orange, with a good battery/charger it would probably have sufficient charge to power on.
If it's blinking solely green you have a notification and the screen is too dark to see when you press the power button.