I switched out the ROM from my Arduino, flashed with this code:
http://opengauge.googlecode.com/svn/...no/mpguino.cpp
After taking it apart, I couldn't see any visible damage to anything. Upon starting it up, I realized that it most definitely was not the same version of code that it shipped with - brightness is inverted (3 is dimmest, 0 brightest) and the buttons are a lot less... responsive, so perhaps the unit I have had your modified code already.
The results of the new chip: gallons per hour reads properly, but I can't get it to read the VSS now. Or, perhaps, I can't find a VSS delay setting that works properly? With a delay of 2ms I get a reading but it's low by about 20%, while a setting of ~250 (like I was using before) gives no reading at all.
I will probably figure it out before you respond (by reading your thread properly) but I can't flash your code with the Arduino software.
EDIT: Line 225 ^^
EDIT2: "#define useLegacyLCDinvertedBrightness true" doesn't seem to fix the inverted brightness settings. I also tried manually changing "const uint8_t brightness[] PROGMEM = { 0, 41, 84, 128 }" to "{ 255, 170, 85, 0 }" to no avail.