Onlci and no boarding
 

If I have done an online check in for a flight on EK and printed the boarding pass however, I did not board the flight.

Is the coupon for that flight is considered to be used and I can use the next coupon without being catagorized as non using coupons in sequence or I still can not use the next coupon and my ticket will be considered as illegal ?

Whether you check in online or not, it is still a no show. The rest of your itinerary is likely to be automacically cancelled.