[RNajarian]

Found a a TSB on the issue. . .

https://static.nhtsa.gov/odi/tsbs/2019/MC-10169751-0001.pdf

From what I understand from the TSB, it looks like you need a PIWIS to manually change the date.

Stay tuned. . . I’m still looking.

UPDATE

From Rennlist, start reading from thread #107

https://rennlist.com/forums/cayenne-955-957-2003-2010/1099700-can-t-set-the-date-8.html

From the thread. . .

#107
“You can disconnect the power harness or disconnect the MOST connection to the DVD unit. The PCM has to think that you don’t have navigation. Once nav is disconnected, the date adjustment feature will show up. This is how dumb the design was.

Your era of Cayenne and 997 designed by the Bose system used MOST, fundamentally they have the same design and same logic. If it is easy for you to access the navigation drive. Either disconnect the fiber optic or the power harness will do. Give it a try, you have nothing to lose.”

#110
“E39Nutz, your the man!!! We owe you.
After pulling fuses, nothing. After asking a Penske Porsche dealer, nothing.
Pull the MOST cable, bam, date can be set.
i moved the passenger seat all the way forward and up, and from the back seat reached under, not the easiest cause there is an hvac duct and then the metal frame holding the dvd unit, and we all know porsche connectors can often require 2 hands. MOST only need 1, got my hand in there after pushing down on the hvac duct, disconnected it.
Started it up, got the normal warnings on the PCM that dvd, amp, etc. are no longer connected, just press the right knob to enter, then go to the main screen, hit set, think I got another error so pushed the right knob to enter again, then select set date and bingo, you can change it now!!! Not just the date format anymore, day month and year are now there.“