Before you take it back, try installing the night-mode hack; it inverts the screen (white letters on a black background) and works flawlessly with the Glo for reading at night (I have an older Glo with the brighter light; the nigh-mode hack makes it excelletn for nighttime reading):
https://www.mobileread.com/forums/sho...d.php?t=212162
(Also works on the Kobo Aura HD.)
Once installed, you simply hold down the light switch (the physical switch on the top of the unit) for most of a second, and it'll switch to inverse video; do that again, and it switches back to normal video.
Rob