It sounds like the tank was left abandoned for some time. One would have thought that Ukraine could have found some way of either destroying it or recovering before Russia got it's hands on it.
I was under the impression that many of the tanks that Russia has in so called "storage" require a virtual rebuild before they can be used again in Ukraine. Obviously if a tank has been "stored" outside for years, in all weathers, it is probably not going to be in the best of condition.