# How to calibrate a Kill A Watt meter and understand its hidden service menu [closed]

I found a hidden menu within the Kill A Watt P4400 meter, which is accessed by holding down the Volt and Hz buttons. Although I rendered my meter unable to measure accurately because of my futzing around with the menus, I was able to derive significant amounts of information about the menu.

• In the menu, the Volt button exits, the Amp button is the up key, the Watt button is the down key, and the Hz button is the select key. The kWh button appears to have no effect.
• The menu contains the following entries:
• SEt KWh, KWh Time - selecting it yields a submenu with EnA and dIS (enable and disable). I don't know what this does.
• rAgE Amp: once again, selecting it gives an enable-disable submenu.
• oPEn: not sure what this does, selecting it simply advances the menu to the next entry.
• U110: Calibrates voltage measurement, using the current input voltage as the reference for 110 V. The menu advances to the next entry.
• U220: Same as U110, only for 220 V.
• 1 0 1: Not sure what this does, seems to be used for calibrating wattage/amperage measurement
• 1 1 0: As above; probably also used for calibrating wattage/amperage measurement as well
• all symbols flashing: a test mode for the display. Selecting it has no effect.
• oFF Watt: Sets the threshold for the wattage measurement below which the wattage value will be displayed as zero. The value can be set between 0.0 and 10.0 watts.
• SAVE: Saves settings and exits the menu.

Can someone (who is willing to render a Kill A Watt meter unusable by throwing it out of calibration) fill the gaps on how the menus work, and therefore how to calibrate the meter? I found relevant information here and here, but could not understand how it works.