Factory Resetting a GS748TS

I've recently purchased a "pre loved" GS748TS. Current firmware: 5.0.0.23

Smartwizard discovery can detect it on the DHCP address of X.X.X.159.

Unfortunately it appears to have a password so I can't:

move it from DHCP to static,

set my own password,

setup LAGs,

update firmware, etc.

I've read the "Full" Manual and while the "reset" button is in the index at pages 2-5 and 2-7, these pages don't exist in the allegedly "Full" manual (it starts at 2-29)?????

Scrolling through the manual does describe the location of the Reset and Factory Reset buttons on page 3-20, but nowhere does it describe HOW to conduct a Reset or failing that a Factory reset.

Very happy to put it back to the factory defaults, but based on the supposedly "full" manual I have no idea how.

Any guidance will be gratefully accepted.

Regards,

Mark