Besides just jamming GPS, I'm sure that Russian/Chinese ELINT can produce false GPS signals. So I could see how they could force a drone down by making it think that it was constantly gaining altitude.
However, I think/suspect that the drones don't use GPS, or only in very limited circumstances. Modern INU's/laser gyros are very accurate, and such a drone probably also has a magnetic compass, air-pressure altimeter, maybe even a sun/star tracker system, or uses other beacon systems/frequencies it's operators provide, and all probably have to agree, or anomalous info is rejected.
If the landing gear got mushed a bit, I see that as nothing to hide. It's an amazing capture for them no matter what.
Although I've been thinking more about my fake "unobtanium tech" drones, and from the perspective of the Iranians, hell, even the Russians and Chinese, a real drone is almost as bad.
The best secrets are the software/firmware that control it, and presumably, the proper fail-safes and encryption are in place.
And as to advanced avionics, jet engines, and materials, the trick isn't knowing it exists,
but how to produce it. Reverse engineering one of our drones is about as bad as a program to make one of your own from the ground up. Unlike the earlier days where the Soviets/Russians could copy basic airframes, like the B-29, or the B1B, and it would shave years off their development time, the devil these days is in the details.
They find that the drone has "impossible" composite X in it. It's the strongest of all, but far too brittle, but the Americans figured out some way to enhance it's flexibility, while sacrificing little strength. What does having a chunk of it in your hands tell you, other than, "Yes it's possible"?
Or that their analysis turns up that alloy Y, which is supposedly impossible to weld, was indeed welded for parts of the drone.
Our methods and processes are the best secrets, and those stay at home, even when a big pile of the end results crashes in some enemy country. Some big boring three ring binder full of checklists, QA/QC procedures, and flow charts sitting on a shelf at Boeing, or General Atomics etc. is probably a way more sensitive set of secrets than an entire stealth drone is.