Hi
Can only tell you my personal experoience. I had a "black" for over eight years . Never a problem went into a "collapse" . I thought it had dies but being lazy I left the pot in the location. Was dead for around three months
and then suddenly started to regrow with a vengeance lol.
I have researched the "dormancy" and find that most sources say it doesn't exist or has not happened to them.
One thing I did note was that the roots stayed green and healthy looking throughout the dead period
It is now back and pushing two feet but has not grown with the original vigor.
Check the roots and see if there is any sign of life.
Most people I talked to threw the plant away when this happened lol
gary