Recently I was in communication with one of the CAM Moderator and thanks to him I was able to discuss some details of this case with the seller. To make this really long story short, we have agreed that I will send this tuner to the repair shop for full, independent assessment of the existing damages to receive an estimate what needs to be done to get a clean bill of health to this unit. After it the seller will make a refund to my account.
I would like to express my appreciation to the really patient CAM moderator who was willing to spend his time to communicate with both parties to solve this really ugly case. I will keep you all posted how it is developed.
Thank you all for your comments!