How to power down the A13 so it does not corrupt Nadnd or the SD

[BJFreeman]

Got my A13 and read the manual page 8, that said

Important!Avoid disconnecting th pow r supply whil Android or Linux is running,sinc that
might corrupt the operating syst m and you will ne d to install the OS again (for Android install
instructions check chapt r 2.6.Us the PWR_BUT before disconnecting the supply.

Now I found the button on the schematic but on the PCB DRW or board.

what have I missed?

as a result may have damaged the board.
I would like to not do this again to a new board.

[BJFreeman]

John pointed out the button is near the power Jack which I totally missed.
now I can bring my my new board