As someone who knows folks who got wrongly blacklisted.. Well, you pretty much never get back. No matter what you do.

You're lucky if you get a decent reply from customer support to begin with..

Your best bet is to change domains, fill in a redirect and try to build up backlinks again. It'll take a year or two and hopefully no competitor pops up in your space.

Or, you can try and get Andreesen-Horowitz interested in your business.

I have helped sites with over 2 million backlinks and got them out of manual penalty in under 3 months in very competitive verticals like travel & finance.

It entirely depends upon the scope of penalty. Unless you are completely deindexed from Google search results, you can always recover from a penalty.

Feel free to email me if you have any specific need.