If you already change the battery with a new one and still have the same problem this unit may have problem inside its circuit board so if you want you can take it to a repair center near you or check this link tey repair this kind of device http://www.thewizardshop.net/5.html
If I may add to the possible fault as described by marked.
Other possibilities could be:
the battery terminal inside the Sharp Wizard OZ-770 are corroded. They have to be cleaned and scraped to ensure maximum contact to the batteries. Further, there may be times that these terminals would have to be bent a little to add more pressure on contact with the battery. If they are spring type, they may have to be stretched a little;
a disconnected battery wire, chances are the red or positive wire has been affected by the battery acid and was cut. It would have to be soldered back after a sufficient length has been removed to ensure that no more corrosion exist on the wire. In some extreme cases, the entire length of wire might have to be replaced;
the on/off switch. for the diagnosis and repair of the switch, the unit has to be opened and the switched tested with a continuity tester (DVM). Though sometimes it may be cleaned, it is preferable to replace if found defective.
Hope this be of initial help/idea. Pls post back how things turned up or should you need additional information.
Good luck and kind regards. Thank you for using FixYa.
have sharp oz 770 and characters on screen are washed out and some not readable batteries ok any fix...
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have sharp oz 770 and characters on screen are washed out and some not readable batteries ok any fix possible