Of course China wanted to "re-negotiate". Chinese culture, whether in government or business, seeks to sign a contract first, then negotiate the terms after. In America it's called "reneging". In China is called "that strange, silly, sign a contract game the Americans require that makes no sense". Trump has known that since he had his ties made in China, maybe earlier.
Now, the American provocation machine is in full-swing. An executive order banning Huawei and a DOJ prosecution of Chinese hackers—all while planning another meeting in Japan next month—this isn't failed diplomacy. In the past month, China lobbed one too many objections to US action, thus providing the telemetry the US needed for the final calibrations on the Chinese irritation machine. That machine is up and running and won't stop. It will keep producing irritation at the speed of a 5G network.
As said last week, the problem of the F-35 was already known because the US was no longer interested in searching. This week, we found out the specifics: a fuel tube. Now, we just need to wait for distribution and replacement to get set up.