I have tried shutdown with this
Java.Lang.Runtime.GetRuntime().Exec(new String[] { "/system/xbin/su", "-c", "shutdown" });
and this
Intent i = new Intent("android.intent.action.ACTION_REQUEST_SHUTDOWN");
i.PutExtra("android.intent.extra.KEY_CONFIRM", true);
StartActivity(i);
Thank's all, i have read in another post
i use this for shutdown imediatly
Java.Lang.Runtime.GetRuntime().Exec(new String[] { "/system/xbin/su", "-c", "reboot -p" });