Not the engine though

Just driving along about 20 minutes ago and i flashed the headlights. The car just died!!
All that came on the dash was the red battery light and then it stoped. There is no dashboard lights and the car turns over but wont fire.

I have checked all the blade fuses under the bonnet and they are fine, could it be the ignition rely, if so where is it???

Also when i took the ECU cover off the Earth strap that goes on the screw of the ECU wasnt connected, would this of coursed it???

Help need please