Blackberry Priv (unlocked) not updating with AT&T prepaid card in AT&T network
I live the European Union. I bought a Blackberry Priv (AT&T unlocked) on eBay. It was delivered to my friend's house who lives in Michigan, USA. He is leaving America for Europe in a few days.
After reading these forums I understood that the great bargain was actually a bad deal. I informed him about updating problems I will have in Europe. He tried to update without a SIM card and got an answer: ""No update is available for your device at this time. Please try again in 24 hours."
Then he purchased an AT&T sim card and one month's phone service for 25 USD. At home he made sure it is registered in AT&T network by trying to make a call.
After that he tried to request an update, by tapping Settings > About > System update > Check for update. Every time he receives an answer: ""No update is available for your device at this time. Please try again in 24 hours." After 24 hours - the same.
The phone has Android 5.1.1 on it, so there should be 8 updates.
What is wrong? What should I do to get updates while my friend is still in the USA?