Well, the customer "stating" this would not be enough. They would have to show a great deal of documented proof such as invoices, employee records and records of sales to their customers. They would have to explain why they needed small sums of money from Rossi to pay routine expenses. They would have to answer many technical questions from experts, such as how they managed to use all that heat, in what sort of industrial process, why they did not heat up the building, and how they operated without people in the production area, and without noise. They would have to explain how they managed to use 1 MW of process heat with only ~4 kW of machinery.
The customer would need a 1-MW capacity cooling tower outside the building, like the one you see in the photo on p. 4 of this brochure, where it says "Ready to use in an instant."
http://www.viflow.fi/uploads/coolingtowerseng.pdf
I think they would need something the size of the OCT01 model shown on the next page. No one saw anything like that outside the facility. I do not see how they could magically hide it. You can't put it inside the building.
All in all, I think it is out of the question.
Rossi claims "the customer" does not want to describe their secret industrial process. It turns out the customer is Rossi and his lawyer. They are the owners and the only employees of the company. So if he wants the money, he -- the company, that is -- better change that policy and describe the process in enough detail to convince people it is real.
Needless to say, that is all nonsense, as anyone who does not live on Planet Rossi can see.