IF it is like the 90X models, then you open the cover at the back by sliding it. You want to be good mannered with it
Check this out:
https://www.mobileread.com/forums/sho...11&postcount=2
also, make sure your battery is fully charged, as that also seem to be giving problems. Even if it looks like there is enough charge, you should charge your device for a few good hours before use.