Hi, I have a Dell 2700w rack UPS and I would like to set it to High Efficiency mode. It's currently in Normal mode. I'm able to get into settings from the control panel on the unit, but can't seem to change the settings. I've also tried to reset the settings to defaults, but can't seem to do that either. Has anyone else experienced this? The manual says the unit needs to be "stable" for a minute before I can change the High Efficiency setting, and I've even unplugged everything, turn off the unit and waited for 5 minutes and still no go. Could there be some type of user "lock" I am unaware of? Thanks!