I was about to call you out on the model number but instead I learned of a new, UK-only Amiga model. I did chuckle when reading that under the A1500 label is an A2000 label.
Sure, if the workbench was loaded, you could start a shell and write a script (with that awful built-in line editor, uuugh), but it wasn't the same as the instant-on of the C64.
I used to do similar things at Radio Shack; there was a POKE you could use to toggle the internal relay on/off much faster than you should (the BASIC command to toggle the relay would wait a second or so before each state - the POKE obviously didn't). Put this in an infinite loop, walk away and watch the poor clerk run to the front of the store to reset the demo machine.