FYI - I often have some Pi/MightHats at a desktop in my bedroom and the power led can get bright. I added the following code to turn off the power LED when the LCD brightness is selected to 0.
The code is in the handle2Buttons() function
if (backlightLevel==BACKLIGHTLEVELS)
{
backlightLevel=0;
POWER_LED_OFF(); <------ Added this within the new braces
}
else
{
if (PowerState == ON) POWER_LED_GRN() else POWER_LED_OFF(); <------ Added this within the new braces
backlightLevel++;
}
LCD_BACKLIGHT(backlightLevel);
sprintf(lcdbuff, "LCDlight:%d/100", 100*backlightLevel/BACKLIGHTLEVELS);
refreshLCD();
Or you could use a simple photoresistor/LDR to read ambient light and dim both screen and power LED accordingly.