Manual
https://dl.dell.com/topicspdf/optiplex-5050-desktop_owners-manual_en-us.pdf
AMT
https://community.spiceworks.com/t/dell-7050-amt/639076/6
https://www.dell.com/community/en/conversations/desktops-general-locked-topics/what-is-the-mebx-hotkey-on-a-optiplex-7040/647f70fbf4ccf8a8dee8bbbb