Comment 4 for bug 1751956

I poked at this with gdb:
#0 gsd_power_backlight_abs_to_percentage (min=min@entry=0, max=0, value=-1) at ../plugins/power/gpm-common.c:61

that should trigger g_return_val_if_fail (max > min, -1) to return, however the g_return_val_if_fail's seem to have been compiled out ;(

I will file an upstream bug for this