None of that (legally) ought to (directly) block a conviction. The defence is entitled to move for a mistrial, or as they actually did, appeal for such. Without that though the case proceeds and is adjudicated by the jurors present, on the assumption that what they're told is true.
Now, I don't think the defence is wrong to move for a mistrial. To me, the juror lying on their questionnaire would be enough for that. On the other hand, the jury vote was unanimous. Every person who was asked to judge the facts presented agreed that they showed Chauvin did commit the crimes he was accused of. Did they feel pressure? I'm sure the answer is yes. If you think the only pressure they felt was to convict though, I think you're mistaken. Further, if 12 randomly selected and (however imperfectly) vetted jurors agreed unanimously on all counts, I would suggest that the position that he's not even guilty of the least charge is somewhat of a niche view in society. In short, both the court and the general population would seem to disagree with you.