There are two things you can do, either get a 2 year CFI or call the local FSDO and ask an inspector for a ruling.
by the way, you deserved to fail the checkride and you should have familiarized yourself with the checklist.
Here is a menomic device which might help you and YOUR students
T
L
C
when taking the runway for takeoff, everyone needs a little tlc (used to mean tender loving care)
but for flying
T for transponder
L for lights (have your landing light on for traffic avoidance etc)
C for compass: check your compass, runway "heading or bearing" (using the number or look up the bearing of the runway in the AFD) and your directional gyroscope or other direction indicating device.
TLC
And you have just learned a cheap lesson. YOU and YOU ALONE are responsible for the safe and legal completion of a flight.
the checklist that you used got you into the air safely enough, but you must know from now on a checklist that YOU HAVE not verified yourself may not be as good as the one from a previous FBO.
Why not take a practice check ride with the same Examiner and maybe learn something.
Becoming a CFI is a huge responsibility . YOU are going to train someone who will be flying around the rest of us and that person might be trained "WRONG" and cause a problem.
Be glad you learned something and be demanding of yourself and your students. BE glad you had a tough examiner!