> And there are tons of back alley trained BGA repair specialists in China for mysterious reasons

In some countries it is cheaper to repair a phone than to buy a new one. This creates the "back alley trained BGA repair specialists".

When i was first employed in a Eastern Europe country, our computer supplier will "repair" RAM modules this way. Test was simple: insert in PC, see if it boots. It was the only place where i saw Windows 2000 crash more than Windows Me.