I haven't seen or heard of that. The light usually goes off after a while no matter what. And the PC seeing the device at all is unusual. The only things I can think of is to try a factory reset while starting the device (see
https://wiki.mobileread.com/wiki/Kobo_Reset:_Glo_HD) or trying a new SD card with a new image. I've sent you a link to an image to try.