Commercial Off-The-Shelf (COTS) automotive inertial measurement units were subjected to severe accumulative stress conditions: thermal shocks (high temperature gradients), temperature cycling (low gradients) and mechanical vibration are combined in an A-then-B sequential testing procedure, with the aim to promote failure acceleration and improve lifetime prediction. The maximum stresses, applied individually, did not cause failure on the selected components. On the other hand, accumulative bi-parameter testing conditions resulted in die attach delamination. Three batches of devices tested with different preconditioning (A-then-B or B-then-A) display different reliability figures. Failure mode and effects analysis (FMEA) is established. A Finite Element Analysis (FEA) is done based on a destructive physical analysis of the devices to confirm the correlation between the stresses applied and the physics of the failure in order to understand the thermomechanical behavior of the devices, linking it to observed failures.