Here's a couple of reports, sounds like they had an indication of damage to a brake or gear (e.g. tire pressure zero and/or brake temp high). They didn't want to raise the gear again with possible damage but wanted to burn down to landing weight so they pressed on to JFK after looking at the gear down fuel burn numbers. At least, that's my best guess.
Nov 3, 2018 Following the technical issue it encountered on 1st November, British Airways Boeing 777-236ER G-VIIR departed Orlando in the early hours of this morning operating the delayed BA2036 Orlando – London Gatwick of 1st November as BA9601. Around 40 minutes into the flight at 37,000ft a further technical issue became apparent and the aircraft descended to 15,000ft, dropped the landing gear to cool overheating brakes and turned back towards Orlando before turning around again and heading to New York JFK at a maximum of 20,000ft. Late at night the aircraft operated BA2272 New York JFK – London Gatwick.
The BA Source ? British Airways News and Information
Incident: British Airways B772 near Savannah on Nov 3rd 2018, brakes problem
By Simon Hradecky, created Sunday, Nov 4th 2018 22:40Z, last updated Sunday, Nov 4th 2018 22:40ZA British Airways Boeing 777-200, registration G-VIIR performing flight BA-9601 from Orlando,FL (USA) to London Gatwick,EN (UK), was enroute at FL370 about 70nm southeast of Savannah,GA (USA) when the crew received a high brakes temperature indication, descended the aircraft to FL200 and lowered the gear. The crew subsequently set course to return to Orlando, but re-decided to divert to New York's JFK Airport. The aircraft landed safely on New York's runway 31L about 2 hours after leaving FL370. The crew stopped on the runway and requested emergency services to check the brakes, in particular of the #3 wheel.
The airline reported the aircraft diverted to JFK due to a minor technical problem.
The aircraft had arrived in Orlando on Nov 1st 2018 as flight BA-2037, but did not depart for the return flight BA-2036. About 32 hours after landing in Orlando the aircraft departed for London Gatwick as flight BA-9601.
The aircraft remained on the ground in JFK for about 20 hours, then departed for Gatwick as flight BA-2272 and reached London about 6 hours later.
https://flightaware.com/live/flight/...400Z/KMCO/EGKK
https://avherald.com/h?article=4bfd9449&opt=0