The only one on bitmain homepage:
Antminer-Z9-Mini-NAND-500M-201808311812.tar.gz

I tried both, keep settings and also unchecked it.
Did it several times and tried every combination.

the only tiny success:
installing batch 2 firmware --> change to turbo --> keep settings ---> install original firmware
Result: 550 frequency + working temperature sensor + working fan

sadly this trick does not work with batch 1 firmware and (e.g.) 650 frequency.
Keeping setting and reverting to batch 3 firmware resets the frequency to 500.

Do you understand this thread is for the Z9 (not Z9 mini) ? ? ?

And for z9 mini you should be in this thread:
https://bitcointalk.org/index.php?topic=4610213.msg46938023#msg46938023
and there you will find permanent link to the may 26 firmware for the z9 MINI.