Turns itself back on just after I shut it down?

Hello,

It sounds like an issue with the ignition switch.
It is likely shorting between the pins making the vehicle to turn on.
The ignition switch is the electrical component that the lock cylinder attaches to.

Over time you could have contacts that gets worn or corroded and shorts out. This can create issues with starting.

I have included the testing instruction for the ignition switch (look below)

Please let me know of any questions.
Thank you.