B-2 Spirit has never been officially confirmed to have been downed by any credible report ever. However, the B-2 Spirit has been involved in multiple accidents where the cause was either an accident or mechanical failure and not fire by an enemy. The known incidents can be summarized below:
B-2 Accidents Crashes Information:

Feb 23, 2008 Guam Andersen Air Force Base (February 23, 2008)
Cause: The sensors in the aircraft got wet leading to wrong readings when taking off and this caused a stall.

Result: The plane came down soon after takeoff with both crews ejecting safely.
Was it brought down? ❌ No, it was just a technical failure.
September 14, 2021, Whiteman Air Force Base, Missouri (US)
Reason: There was a crash on landing. We do not know very many details, but it was not the doing of the enemy.

Result: The airplane was damaged and an investigation followed.
Did they bring it down? ❌ No: again, no hostile action.
And When you are referring to the rumors or conspiracy theories about a B-2 being shot down {e.g. in Serbia or over enemy territory), those rumors are ill-founded and have no track with any noteworthy military or intelligence authority.
You want to know more about the 2008 hotel crash or the stealth potential of the aircraft and why it is hard to shoot it down?

You mentioned:
Do you want some more material about the 2008 crash or about the abilities of the aircraft to be invisible and the explanation of why we cannot aim the gun easily?
ChatGPT
Excellent! We should examine both topics, the 2008 crash, as well as why the B-2 spirit is so difficult to kill, since they both closely relate to understanding what makes the aircraft so survivable.
B-2 Spirit Crash 2008- Andersen AFB, Guam
📅 Date:
February 23, 2008

📍 Location:
Andersen Air Force Base, Guam
🧑✈️ Crew:
Two pilots parachuted out without damage.
⚙️ Cause:
The plane crashed because moisture got into the air data sensors of the aircrafts, also incorporated in the flight control system.

These sensors fed the flight computer with wrong speed and angle-of-attack data.
As a consequence, the aircraft prematurely rotated during take-off and stalled and crashed.
📉 Result:
It was a total loss of the machine with a rough estimate of its value at $1.4 billion.
It became the first B-2 loss since its development in the 1990s.
🧪 Investigation:
The Air Force did not find the problem caused by the pilot error, however, it was a malfunction in the software/system caused by the faulty sensor data.

Why the B-2 So Hard to Shoot Down
B-2 spirit is one of the most vigilant and robust aircrafts that have ever been built. These are the reasons:
Hidden Shape and Materials
The fly-by-wire bridge structure of the B-2 minimises its radar cross-section (RCS).
The radar-absorbing materials (RAM) are applied on the aircraft to absorb the incoming radar signal.

Low Infrared (IR) Signature
The engines are covered in the wing to make their heat fishing difficult to the targeting process of infrared-guided missiles.
Radar Cross Section (RCS)
It is also the size of a bird on radar.
It is almost invisible to first-warning and surveillance radars and particularly those which are less up-to-date.

High-Altitude Penetration
The B-2 flies at very high altitudes and often outside the effective range of most of the available surface-to-air missiles (SAMs).
Electronic Countermeasures
It is equipped with advanced electronic warrier systems which are used to overpower or deceive enemy radar and the missile detection technology.
Mission Planning
Missions are extremely well rehearsed through satellite intelligence, route analysis, and simulations of the likely threat so as to fully avoid the aerial defenses.