From the BEA report:
Until impact now the stall warning activates when the nose is lowered and silences when the pitch angle increases. FDR data suggest that as soon as the stall warning activates the pilots react with nose up inputs which cause the stall warning to silence again.
I can hardly blame the pilots. If something you do silences a warning there's a natural temptation to keep on doing it.
Horrible systems design I say.