Galaxy Ace gt-s5830- Unable to complete hard re-set

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Hi,
I forgot my pin and have tried the re-set "push the three buttons together" to restart but just came up with an error not options.
I now have it connected to the computer and its saying downloading however I'm not sure where too go from here to re boot the phone with out having to download all this files wanting to take over and make changes to me computer.
Any assistance would be greatly appreciated.
Jess