Things may have changed, but I understand that the jury may interrupt court proceedings at any time - they don't have to wait until being sent out. One does this by signalling to the usher, who will then pass a written note to the judge. It's then up to the judge to decide whether something needs clarification. And the jury may ask for a trial to be abandoned, and deliver a Not Guilty verdict, at any time after the Prosecution have presented their case. In other words, they do not have to wait until the end of the Defence, nor the judge's summing-up. Of course, if it's a Guilty verdict, they've got to sit it out to the bitter end.
There were no jury interruptions in the two cases I sat on, nor do I recall us asking any questions of the judge during our deliberations. But I don't think either of these things are signs of an incompetent jury.
Of course there was no internet then. A lot has changed, since.