2008 Honda civicv ex won't start green key light

https://www.youtube.com/watch?v=dHdzzJGCogA

Watch this video to find the starter relay inside the car.

Even with the reprogrammed key's the engine would crank, it might not start but it would crank over so that leave's only one thing, your used ignition switch is bad.

Did you get the key switch checked out ? The dash indicator lights have to be on for the engine to start. So you are not getting power to the dash lights, and probably not to the computer or ignition coil either.

I would have the ignition switch checked, not the key switch but whats behind the key switch. Ignition Switch!

check your battery connections then charge the battery over night then check the charging system

check your battery and terminals first.... clean or replace as needed. After that check your fuses. After that if you arent comfortable with automotive work, take to a shop. Good luck!!!

Your problem is not descriptive enough. Has it always been like this or just started happening? If it has always been like this, there is a possibility of a faulty lock OR someone has the door lock replaced and in that event, a new one from Honda comes with a new key that is different from the one for the ignition and the trunk and the glove box. Please provide more details.

Sounds like the ignition switch is worn out(or the linkage from the lock cylinder to the switch has come loose or something like that)

Check with dealer most keys now days are programmed to the car you may need to have the new key programmed to your car.

Replace the ignition switch that screws onto the back of the lock cylinder, they were a very common problem and actually subject to a recall. You could phone a nearby honda dealership with your VIN number and they may replace it for free.