Depends on whats been damaged internally-such as any loss of structural integrity-ie ribs/stringers/wiring/hydraulics etc.
If it was a straight forward hole in the pressure hull it could have been temporarily patched over and flown back unpressurised (ie lower level).
It obvisously more involved than that though-so they have probably had to refer it to Boeing for an approved fix. This might mean having to wait for Boeing to produce drawings and fabricate replacement parts etc.