Very good! I found the begin() statement and commented it out.
I reckon I should use the backlight for my LCD, then. I searched and found this schematic that turns is on and off. I cuts the NEG side, but I reckon the POS side isn't connected to the LCD's POS, so it won't back feed into it when I power off the LCD's chip. Not sure about the value of R7. Running from 4.5v, I may not need a very high resistor?
One thing I don't know/understand. When I power down this circuit by a LOW arduino pin, there won't be any current left flowing in the BSS1338 mosfet, then will there? See the attached clip from the BSS1338 data sheet. Does that mean there'll be .5 uA current loss all the time? Accord Nick Gammon's arduino power page, I can get the Atmega down to .335nA, so the current in the BSS1338 is considerable. I reckon the one controlling my H-bridge will add another .5uA.