Battery leakage is major cause of unexpected problems.
Please do not use damaged battery like at the image.
Batteries must be inserted correctly with respect to their polarity.
(Follow the directions on the case)
If a battery is inserted the opposite way, it will start to be charged by the other batteries.
This causes a chemical reaction inside the reversed battery.
There is a risk of explosion or fire.
Do not mix different battery brands within a device.
Doing so will reduce overall performance and may also cause battery leakage or rupture.
We recommend using the same brand batteries within a device.
A trace or copy of a fingerprint can not be used because the system identifies live skin tissues by applying 508dpi hi-resolution sensor