Find a new accountant, even if they cost $500 they will very likely save you thousands, making it worth it. Something feels like it's missing.

If another accountant still says you owe tens of thousands, consider hiring a lawyer specializing in accounting like another commenter suggested.

Filing an extension doesn't help you unless you are going to extend AND pay the 25k by April 15. Which is totally acceptable and you will get that money back when you file your tax returns.