There is a good chance that your EBB is permanently damaged. Tightening the screws at the thinnest part will destroy the bottom-bracket threads. When I was a novice Nomad owner, I made this mistake, and what happened is that the bottom bracket started to unscrew itself from the shell as I cycled. Only the purchase of a new EBB shell from SJS gave me a working bike again.
Sadly, many local bike shops have never seen an EBB, and you really can’t trust them to properly do maintenance on one. At best, you can only emphasize beforehand that the screws need to go into the thick part, but this message might get lost as the shop clerk hands the bike over to one of his mechanics.