Liquid ZEST plus - FlipCover task info ?

I don't think the update is available any other way, other than OTA.  As far as I know, ACER does not have any software suite to allow manual updates of firmware.

For the multiple sim cards, I did not use it much.. I tried putting 2 cards in my phone, and under "SIM cards" option in settings, you just enable BOTH cards (radio buttons to enable or disable each sim), and I did receive texts on both sims.. So for SMS at least, I know there were both active and no issues to receive SMS.  Now for Phone calls, I did not try it..  

I know you can select your default the default provider for Cellular Data, SMS messages, and for outgoing phone calls (If I remember correctly you can select one or the other, or "Ask every time" for phone calls.  

For the update, you can try checking again over the weekend and/or next week.  Sometimes the servers are overloaded or sometimes even unaccessible.

PS: Since you GOT your phone, did you ever get any update on this phone ?  When I got mine in December, as soon as I finished setting it up, it took a system update which brought my Android Security Level to October 5, 2016 pretty much right away, and Broke DTS.  And then I got this latest one on Feb 7 which brought the Android Security Level to Dec 5, 2016, which fixed mostly everything (including DTS and the weather).

Unfortunately I can't check any more since all 3 of my phones are already updated now.

Definately something has a glitch.  I'd try first by shutting down, removing the sim card, and then try again.

One issue I also had was a defective SD card.  Daughter's phone was experiencing strange behaviour, and wifi/data disconnects.  After some checking, it turned out that the SD card on her phone was defective, and sometimes it could not be read.  And having formatted it as internal storage (instead of portable), android had copied some of the apps onto it, and they could not run and phone would be acting funny. Moved as many apps as possible (whatever could still be read) back to internal storage, removed the SD card, uninstalled the apps that it thought were still on the SD card, and reinstalled them, and all the funny behaviours went away.

Got another card, but this time I installed it as portable, and she uses it just for map downloads, photos, and her music downloads.  The internal 16GB is plenty for the apps.

I know I hate Factory resets, and I was skeptical myself.  But backing up my photos (if you are not using google photos - which auto backs them up), and any other downloads you may have done is all that is needed.  I have my phone syncing to my google account and after a reset, it asked me if I want to restore from a previous backup, and if I wanted to restore all apps, or just some of them.  I custom selected the ones I wanted to keep (oppurtunity to clean up), and it redownloaded all the apps I had, and restored all the settings also of most apps.   Even managed to restore all my WiFi passwords, which was pretty sweet.

OK, noone wants to do a factory reset, but sometimes it is the only option

PS: If you do manage to take the latest update, keep in mind that after first boot, just do a basic configuration, because to MAY require another Factory Reset to be able to re-enable the broken DTS..  In your case, your DTS is NOT broken, so you may not need it, but just something to keep in mind.

IF you can live with the bug, then don't bother with the update..  I was pretty much ready to live with it, since it was a minor annoyance.  But the first update also broke DTS, which for me was one too many issues to live with, and wanted at least something cleaner.  If it was just the temprature on flip-cover, I would have probably just lived with it, if it required a reset.

Restoring DTS functionality was worth the reset.  But just for the temprature, not sure I would have reset.