I don't know your situation or how much you want to get out of it. But one option would be to convert half ($2M) for $1.50. That seems like the obvious price to me because it was supposed to be the bottom price.
Turn the other $2M into an ordinary loan, promissory note, or whatever you have. You should be the expert on this. If you don't need the money immediately, that is.
I understand it's the company's fault. But we simply can't have this toxic note outstanding on a $600M net asset company. And the main reason is, the crowd doesn't know it's a friendly loan. Even if it is a friendly loan, I don't think it is acceptable.
You are up to your neck in this investment already. So that's what I would do.