How do I upgrade my version 9.3.5 model MD528LL/A

By “upgrade”, if in fact your question is how do you update the installed version of iOS, then I’m sorry to disappoint you...

Your iPad mini is a 32-bit A7 processor device - that is no longer supported for iOS updates; for a Wi-Fi only device, 9.3.5 is as far as it goes.

That's a WiFi-only first generation iPad mini. It can't be updated past 9.3.5.

(175747)

That is a WiFi only model, thus no update required.

We have already told you that MC769LL/A is an iPad 2 Wi-Fi which isn't affected by the GPS Rollover and therefore there is no 9.3.6 to update to. It was only released for the Cellular versions.

You are welcome.