Catalytic converter repair issues

My daughter and son-in-law have 2 Prius, a 2004 and 2008. Both had the catalytic converters stolen the same night. The 2004 was declared a total loss, but the 2008 went to the dealer to install a new catalytic converter. When the car was picked up, the red triangle of death showed up which had never been an issue prior to this repair. The dealer said it was an older battery with just over 200,000 miles and was ready to go out. Luckily, the 2004 had a battery replaced by Green Battery company about 3 years ago and was still working fine. I swapped the battery and all was good to go. About a month ago, my son-in-law was flying from the Denver airport, and on returning, it became apparent that the catalytic converter had again been stolen. Furthermore, it went to the dealer for repair, but here is the really odd thing. As soon as it was picked up, the red triangle of death again showed up. Was this just a coincidence? I am beginning to think that something was done by the dealer to cause this fault to make another 3-4 thousand dollars from an out-of-towner. Have anyone else reading this had this happen?