Firstly, turbocharger not advised to be sent back,as delivery costs much.
If there meets a problem, we firstly ask for the pictures for damaged parts.
And base on the pictures, we could have a basic idea of  the defect causes,then proceed with best solution.
Turbocharger is a different product, sometimes the defect is not because of the turbo quality.
For example, if there impurity inside, it will also cause the defect.

Impact damage caused by foreign material entering the turbine housing or compressor housing is clearly visible on the turbine wheel or impeller.
Never continue to operate a turbocharger with damaged blades as the rotor balance will be affected and this could impact its service life.
 

When analysing possible turbo-charger problems please remember the following:
Turbochargers are very reliable: less than 1% of turbos fail due to a manufacturing fault with the turbo itself.
95% of turbo failures are because of problems with oil starvation, oil contamination or foreign object damage
Before you fit a new turbo, find out what caused the first unit to fail or you risk the replacement failing too.