jelecroy wrote:
You might try to see if you can find a known-good battery. If the battery in your D90 is tired (entirely possible with a ten-year-old D90) it might have enough voltage to show as fully charged, but still not be able to supply sufficient current to operate the on-camera flash or focus motors. It may be a long shot, but is one issue that could cause both the dark pics and lack of autofocus.
I will try that. Thank you