Hi. If you removed the batteries to do a reset, you should have heard three beeps when you turned it back on. If not, then you have not RAM cleared the machine. Make sure the key is set to REG mode, turn off at wall for 5 minutes, turn back on, wait for three beeps, then put batteries back in. If you still have the problem, then it is a hardware fault.
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If anyone needs a manual for a Sharp XE-A102, see here:
http://the-checkout-tech.com/estore/catalog/product_info.php?products_id=602
Mark
February 2010