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Check the battery terminals. If they are corroded, or broken, then the calculator will not get power.
That sounds unlikely since you say it is getting power. How does it indicate that, by the power light coming On, but nothing else, and nothing happening nor responding? If that's how it is, then it may have a failed central processor or circuitry in control of it, and be fairly thoroughly 'broken'.
How old is the calculator? if less than a year old, it might be covered by warranty from Sharp Electronics. Let me know, and I will advise you further.