Hello Jenanne,
Not all the dc dc regulators have the capability to manage the pre-bias and the high input voltage ramp up rate.
If the regulator startup under-prebias condition and it doesn't have any protection or pre-bias feature it could be damaged because most of the energy of the pre-bias will be discharged inside the low side Mosfet of the regulator during the startup and this could be higher than the MOSFET capability.
The high input voltage ramp up rate will cause high inrush current that could damage the high side MOSFET of the regulator.
REgards,
Mostafa
