The AIMS is known to have been working as it supplied positional data to the SATCOM till the end of the flight.
James Nixon wrote an entertaining book but he made several errors in what he asserts.
*22 minute oxygen generators- Yes they supply oxygen for 22 minutes. However, the amount of oxygen they supply tapers very quickly on the assumption that the first thing the pilots will do in a depressurization is begin to descend as per the checklist. Passengers and cabin crew will become hypoxic very quickly if the descent is not carried out expeditiously
*Pulling down one oxygen generator activates all of the generators in that seat row. There were 8 vacant seat rows in the cabin; 7 in business class and one in economy. There was very little spare oxygen available elsewhere, apart from the 15 attendant bottles. If the cabin was depressurized, the 4 litres/min these bottles supply would not be enough to maintain consciousness at 35,000 feet due to insufficient pressure.
*There is no indication in any of the recovered MH370 wreckage that a fire was involved.