I am also having this problem.
Bought my model, a UM7000PLC, a few days ago and was working fine until today where I tried updating Prime Vídeo. Just would not let me.
Searched online for some troubleshoots and ended up doing a factory reset. Now can't load user agreements and don't have access to any apps...
Tried router reset, DNS, hotspot with phone and nothing. Spent 2 hours on this only to find servers are down... Guess I'll use the Xbox for Netflix.
Hope this gets fixed soon.