Did you take the batteries out when you tried the power off reset?
Manual: http://olsonbros.com/sharp/specs/pdf/ib-xea102.pdf
1. Remove the register from its packing carton.
2. Insert one of the supplied mode keys into the
mode switch and turn it to the REG position.
3. Insert the plug into the AC outlet.
IMPORTANT: This operation must be performed
without batteries loaded.
4. The buzzer will sound three times. Now your
cash register has been initialized. The display
will show "0.00" with “¬”.
XXX
September 2016