The only piece that not fit in puzzle will be rupture of FDR recording. Cables are at the right side, and any evolution you described are well into time frame of discretization on FDR.
Except if, however, information about FDR was correct.
PS: source of bomb placement is
LifeNews but it was not reprinted by any major media yesterday.
PPS: Even "yellow" LifeNews has enough heart to not disclose name of 30A occupant, even less to post photo with "Too young to die ... Maria Ivleva.Source:Supplied" caption...