Without booting MyBIOS first and then the fat-loader:
Yes, You must power-cycle the machine.
(Since the hotkeys are only working with the MyBIOS loaded)
Did you already update the cartridge, if not, perhaps a good idea.
http://www.mr-atari.com/Mr.Atari/MyIDE-ONLY/Number #7 is the latest.
You could ask Steven to buy the reset-button on the cartridge.
This means drilling a hole and soldering the add-on.
Grtz,
Sijmen.