Hopefully it wasn't what some were saying. Inadvertent gear up landing. Looking at photos it looks like the engines have scoring on the undersides. What I heard on the Live ATC doesn't sound very professional. Even the before the go around radio transmissions weren't remotely iaco standard. ATC giving them a heading when they were already established on the ils? what the heck.
Wild speculation but gear issue to a go around followed by no TOGA press or thrust lever advancement excessive sink rate panic go around too low contact ground leads to dual engine failure. Looking at the video looks like they held it at high AOA till ground impact, i'd say whatever envelope protections the A320 has saved them from fully stalling it in.