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There are two potential issues, first is the issue with your OS (which you mentioned) and the potential developing issue with your battery (which was overlooked).
Fully draining Li-ion batteries, the same type of battery that is in your phone, is not advisable - repeated full-drains result in chemical wear and can irreversibly damage the battery. Several users take this advice lightly only to regret the effects (and ironically start blaming the manufacturer) when their phones refuse to turn on.
As for your OS, if it indeed is corrupted, connect your phone to your PC and use the Lumia Software Recovery Tool to re-install the latest stable version of the OS for your L1020. We must mention, however, that a corrupt OS would most likely not start at all - since you apparently can boot your phone up it may be a more benign case. Nonetheless, use the Lumia Software Recovery Tool just the same to be sure... and avoid fully draining your battery next time.
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