Wrong modification done in Tata Nano- Thermostate valve

I have purchased a 2nd hand Nano Std. of 2012 model having clocked 17000 kms. The car looks almost new but while turning the ignition key I found the radiator fan starts first in the 1st stage twisting of key and engine starts in the 2nd stage twist of the key. I took the car to a road side mechanic and after inspecting they found that the radiator fan connection being modified bypassing the thermostat switch. They reworked the same to original connection. I drove the car and came home. Now I think that whether the thermostat valve in between radiator & engine have been removed or not ? If removed then I should refit it again to its normal condition. My question is that whether the engine conditioned became worsened due to running the car upto 17000 kms with faulty/modified connection by the 1st owner ? If I found the thermostat valve have been removed and if I refit the same then what will be consequences arises ?