TRY THIS!
Use the valve extender itself as the tool to loosen/open the valve.
Remove valve extender (Zipp, I assume); flip extender upside-down; insert into valve hole making contact squarely with presta-valve knurled nut; using slight pressure against the nut, turn counter-clockwise loosening the knurled nut; this should open the presta valve. Gently re-install valve extender as designed, tighten. Inflate tire.
A temporary fix until tire replacement/re-glue, but it has worked for me dozens of times.
Use the valve extender itself as the tool to loosen/open the valve.
Remove valve extender (Zipp, I assume); flip extender upside-down; insert into valve hole making contact squarely with presta-valve knurled nut; using slight pressure against the nut, turn counter-clockwise loosening the knurled nut; this should open the presta valve. Gently re-install valve extender as designed, tighten. Inflate tire.
A temporary fix until tire replacement/re-glue, but it has worked for me dozens of times.