EEngr,
That is about right. As a regulator, the FAA has no liability. The FAA validates the aircraft manufacturers self certification.
The FAA's job is to look at the data that Boeing submitted, and make sure that it meets or exceeds the criteria, and that the data provided is reasonable for that assumption.
The significant issue here is that the FAA will now look into Boeings processes, testing methods, and certification procedures. The FAA's subject matter subcontractors will be looking at the process as well. It is already noted that the Naval Labs are looking at the batteries.
Agencies in other States will be looking at this as well, so the FAA will have to at least meet or exceed their efforts...given the liability, loss of service claims, and competition significance, the level of detail should be very, very extensive...
This appears routine to the general public, but looking at the engineering and certification process, this is very very significant.