Whilst I think most people would accept that the "book answer" is to go-around, in the real World the scenario is not always straightforward.
Would the answer be the same if a flight had been holding for 20mins on a gin clear day and in the event of a go-around (if communication could be re-established) a "pan" would have to be declared because of the fuel state? What if the flight had held for a bit longer and a "mayday" would be required in the event of a missed approach?
Would the flight do the same on a CAT3 day?
Would the answer change with the location of the airport? Geneva has a very long missed approach procedure and lots of terrain around. Would I want to commit myself to another 10-15 minutes flight with an as yet potentially undiagnosed problem? Would I feel the same if I could detect the meerest whiff of hot electrical components?
What about Madrid? The techniques and knowledge levels of the ATCOs there fall some way short of what we as pilots would like under normal conditions. Would it be safer to land on a long, apparently clear runway or to throw ourselves back into the sky without being able to tell them where we are going or why?
Having said all that. A simple blocked frequency on short final with no other complication should in my opinion result in a go-around.
G W-H