@darcy Can you connect it with the wire to a computer and open up iTunes to see if it pushes any updates to the phone? Like a carrier update or iOS update. Update all if it does push something.
To comment on how /why things get blacklisted. Some reasons are sellers from FB marketplace / Kijiji etc are plain old fraudsters. It was actually on the news a while back.
Some basically sell their current phone as they want to get a new one. The person buys it. Looks good for a few days, it's working etc. Then the seller calls their phone company and reports it lost or stolen. Phone company blacklists the phone so it can't be used any longer, the seller gets a new phone (be it by their extra insurance they paid or by just ordering a new one) and the buyer is stuck with an expensive MP3 player.
Let us know how it goes after connecting phone to computer.
Other reasons you have low bars,etc could be that the phone itself has issues. Maybe a malfunction antenna or something and the seller did not tell you about it and just wanted to get rid of it.
Keep us posted!
