Strange BlueTit behaviour ..

Hi Sue, no it is definitely Mum .. and both parents are still around .. It's as if she is doing a deep clean of the nestbox, as just now seen her pecking away at the hole !! The remaining two chicks are buried within the nest 'fluff' somewhere ! can't even see them at the moment!! And, whilst all this has been going on, they have not been fed ! so I hope they know what they are doing !! She wouldn't be getting the nest ready to try again, would she ?? Surely it would be too late now ??