A Reboot Fixes Everything, or Does It?
“Have you tried shutting it down and restarting it?” is the first question your friend asks you when you tell them your phone/laptop/microwave isn’t working. A clever fella who came across this elevator sign thought the idea could be extrapolated to this broken elevator too.
You can’t call a non-functional elevator “offline” instead of “out of order” (or any other suitable description) and expect to get away without a witty remark. So, you can say that the writer of the original sign had it coming.