What in the actual ?
Stockholm syndrome?
They do not have any tech, they are not even developers. They are scam artists.
Read the report, the exchange isn't theirs, the blockchain isn't even theirs, and it's corrupt.
I'm sorry that you are holding the bag, I've been there and it's no fun, but cut your losses here.
How is your lead_dev explaining this away today, or has he disappeared like he did with the receiver?