I think what really happened was that CIA operatives likely lost control of the UAV somewhere in Iran and then decided to crash landed instead somewhere close to the Afghan border with hope of being able to recover it instead of blowing up a multimillion dollar equipment. Hence the obvious damage and scratches to the belly of the machine.
Crash landing can be an automated respond of this plane to loss of the guiding signal which could be due to various reasons, signal jamming or just a software / hardware malfunction. There is no real way of knowing what is inside that plane but I will not be surprised that they have tightly integerated INS systems that works with GP signal ( the military code of it) as an additional navigation tool.
Now, if we assume that the original signal was lost due to malfunction, then GPS should have worked and just automatically take the plan back to the base ( the technology is there for such thing).
Now, if the GPs unit failed as well, then the INS should kick in. Again, it makes sense for them to put the INS in a different board so in case of the failure of GPS and Controlling Signals, INS be able to still continue.
Now, as far as INS goes, it really depends on what kind of INS units they have on these plans and again, there is no way of knowing because some of the INS units that US army used are not in the market now and will not be for another 10 years.
The normal INS units in the market today, can not guide this plane back by itself. however, they can probably maintain it while the plane tries to establish connection. If that fails and gas runs down, then these units can slowly guide the plane to a semi safe landing ( hence not too much damage). Also, I heard these planes are designed to glide with their huge wing span which again, can make the landing much safer than normal jets.
At the end, it is so hard to answer these questions when you have no idea what the technology behind it is.