Is it reasonable from a legal point of view to forcibly unlock the lock without paying the house?

Of course it's unreasonable, even illegal.

However, in view of the contract dispute between the two parties, and the other party has paid most of the house price, you will not force him to move out by reporting this matter to the public security. Under normal circumstances, it is still a contract dispute in court, and the court will judge the other party to pay the balance and compensate you for your losses.

If the other party wants to claim the ownership of the warehouse, it is also sued or counterclaimed by the other party. If you say so, the other side's statement should be unfounded.