2015 dodge charger no turn over

I have a 2015 dodge charger r/t, me and my dad installed
long tube headers. we didn't have the rear o2 sensors
plugged in, and we tried to start it but it didn't do anything.
At first we thought it was because the o2 sensors weren't
plugged up, we plugged them up and the car still doesn't
turn over at all the battery is new and the starter sounds
like it does one click that's it. When we were installing the
headers we accidentally touched the starter positive and
made it spark a few times installing the headers. There is a
flashing check engine light now, could it be we the o2
sensors not being plugged in caused a code and that's why
it wont turn over? All the fuses and relays for ignition and
starter are fine