The news said that it was under going testing.
Getting new radar equipment too (engines also being upgraded)...2 Boeing engineers onboard for a test flight:
https://x.com/RyanRuggiero/status/2066686940645060689?s=20
https://www.af.mil/News/Article-Display/Article/4356905/b-52-stratofortress-completes-ferry-flight-after-radar-modification/