When it boots up hold command & R to boot into recovery mode. open disk utility and format the drive you are using. then quit disk utility and open Reinstall mac os sierra. follow the onscreen instructions
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When it boots up hold command & R to boot into recovery mode.
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Open Disk Utility and reformat the drive you are using. Then quit Disk Utility and open Reinstall MacOS Sierra and follow the onscreen instructions.
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Also you can hold shift, control and option to reset the SMC.
When it boots up hold command & R to boot into recovery mode. open disk utility and format the drive you are using. then quit disk utility and open Reinstall mac os sierra. follow the onscreen instructions