CSD16407Q5C: CSD16407Q5C burnt component

Quynh,
Thanks for posting.
There are many potential root causes where a FET may fail, normally failure is caused by electrical over stress. This could be excessive voltage or current being placed on the device that caused it to fail short and conduct large amounts of current which can burn or melt the device, depending on how large the power source is.
How this over stress occurred is normally the most difficult issue to find. It might be an over-saturated inductor, non optimized layout causing excessive ringing in the device and damaging it, circuit issue under certain circumstances causing short to ground, issue with device itself caused by incorrect solder coverage/mishandling during assembly. These are just to name a few.

I suggest you contact your local TI representative to get specific assistance on your issue and see if items such as failure analysis is required.