I did upgrade from 1.6.0.14 to 1.7.6.1 BUT NOT done with 1-click upgrade, and did upgrade to 1.7.6.3 & 1.7.6.4 afterward with 1-click upgrade
Any errors after you performed 1-click upgrade ?! I did numbers of 1-click upgrade, the process will tell you if any errors ?
Have you do the following actions after 1-click upgrade
1. /var/cache/
2. cache/smarty/compile
3. cache/smarty/cache
4. img/tmp
Have you try to install / run a standard PS 1.7.6.4 on the same host ?!
If ALL above does help, you better RESTORE your copy of 1.6 0.14 to resume production system first !
Test on Cloned 1.6.0.14 first ! There is some module doing data migration, like I did in the first step, but I did it on my cloned production first, and make sure they did well before actually do on production system !
BTW, I try entering https://nodesus.com/ and this is what I see. Is it your production site ?! When I click on https://nodesus.com/store/ couple errors on database...
Hope this helps !