Unfortunately, class actions are pretty much a waste of time. Even if successful, the return is usually a couple of bucks for shareholders and large attorneys fees.
In this case, you would need a local attorney, who is NOT one of the class action factories. He would have to go outside the box, outside the boilerplate pleadings, and would have to do a shareholders' derivative action in an attempt to trace assets that have gone to insiders because, ultimately, I doubt there is a significant solid asset base in the corporate entity. Just my opinion and I have not seen anything that discloses where the money from all these dumped shares have gone.
Tracing assets to a scammer involves non-boilerplate type law practice and you need a good hungry local attorney who sticks to it, not a class action guy who just shuffles papers.
From a practical standpoint, the only solution to stopping these types of scams are as follows:
1) SEC
2) State Regulators
3) Publicity - which motivates 1 and 2 and is the bane of the scammers' existence.