Without root you only have 2 options:
1) Fully charge the battery and do Factory Reset. You'll loose all data of course...
2) Do a couple of full charge / discharge cycles, the reader should calibrate automatically.
Maybe there's also a third option: enter recovery console (
https://wiki.mobileread.com/wiki/PRST...covery_Console), be sure the battery is fully charged. Now you can delete the file via
Code:
cd /tmp
mkdir data
mount /dev/mmcblk2p9 data
rm data/system/batterystats.bin
umount data
reboot
Even the unrooted reader has the Testmode app installed and there must be a way to activate it, I'm not sure. But with Testmode app, you can boot into recovery console too.