I need help with my countdown timer project!

Ok, that can be undone as it means you have the correct display.

There is another thing I have noticed, at the top, this is declared:

int segmentPins = {A1,3,4,5,A0,7,8};

but from what I can see from the code, there should be 8 pins

int segmentPins = {a,b,c,d,e,f,g,dot};

But you only have seven. If you are not using the decimal point, you still need to declare a pin for it, otherwise there is a digital write to an unknown pin.