Diagnosis: Piston tipper

Today is really a bad day for me. I left my ABT at the workshop to get to the bottom of the rattle / rattle sounds. This morning I picked him up with the Job’s message piston tipper. Probably. In order to get closer to the bottom he had to take the engine apart, but I refused that. I am really desperate, have my ABT only 15 months and am also quite satisfied and would like to drive it for a long time and the master said that it is not so wild as it goes away when the car gets warm and I can drive with it for a long time, but should I rather park the car somewhere else and get a second opinion? Can that be just a hair crack in the cracker (When I asked the master yesterday he said it is unlikely). What do you think?