Welcome! I see you have tried to clean the battery contacts, was there any notable corrosion on them?
Nothing major, such as batteries that were left in for an extended period that may have leaked or burst?
If there was no major corrosion, the terminals may need a bit more than vinegar. If a pencil eraser is actually one of the best things you can use to clean those contacts. if it still does not work, there is a possibility that the solder joints on the back side of the battery terminals have corroded or broken. if this is the case, it would require dis-assembly and repair. As this is only a 4MP camera, this might not be too cost effective.