Sorry, but Latest firmware
is only true at the time of install
Not knowing when you got this latest firmware
requires asking these questions.
Dec 09, Mar 10, Apr 10 ?
The Mar 10 was pulled because of reported issues, including rapid battery drain.
I use the Dec 09 version to read EPUB, lock screen frequently with no battery charge issues (multi week with thousands of page turns on a charge)
I suggest your mother call Astak Support since the PEz is in her possesion and can perform the tasks suggested by Astak support and report the results.