Balance issues

Ok guys big F!#cking issue and not exactly sure what happened. Had an engine assembled for me for the first time at the machine shop. (Didn't have time to do it myself) Broke motor in and it failed. Had rotating assembly balanced and it burned and spun 3 main bearings from torque converter side forward! Did the shop screw up or is this my doing? Cam bearings didn't fail it ran for 15 minutes?!!!$$$ super confused main bearings were bright blue and black. Insight please? Can I reuse the pistons and rods in another engine?