Q. Can you use an e-reader in Shabbos? What if it is turned off and you are just reading what is on the screen?

A. Please see the previous answer. In regards to using an e-reader on Shabbos Horav Shlomo Miller’s Shlit”a opinion is that it is prohibited, since its use may be included in the rabbinical forms of writing. Besides, as with other similar electronic devices when turning them on you incur in a number of prohibitions such as Moilid, (creating something new) and tikun kely (forming a utensil which is a sub-labor of makeh bepatish or finishing the creation of a utensil and one of the thirty nine prohibited works of Shabbos)

Even if the reader is turned off and you tape over the power button, the tablet may still be muktzeh. Altough the tablet is a k’li shemelachto l’issur, (an object normally used for activities prohibited on Shabbos) and could be used for activities permitted on Shabbos, such as just reading the screen, however, the tablet may also be considered muktze machamas chessoron kis, (a significant object that, if used for activities permitted on Shabbos, may become damaged), and therefore cannot be used.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a