Hi @ghostychan, thank you very much for this detailed information which I hope will be of use to other users who are facing difficulties with the Z271T.
Our sincere apologies for this inconvenience caused, we realise a small number of users have faced this problem and that returning the monitor to original manufacturer is of course not the ideal solution.
We hope that the advice you have so kindly shared will be of use to users in a similar situation as yourself. Best Wishes.