Why would a BMS (or other circuit) have reduced voltage after a short?
Some BMS units can do many things well.
Protect a battery from:
Over Voltage (OVP)
Under Voltage (UVP)
Over current (OCP)
Over Temp (OTP)
Under Temp (UTP)
Battery States SoC/DoD, SoP, SOH (? maybe)
Ground leakage (?)
Fuse current protection (?)  

But input transient overvoltage from V=LdI/dt from a short circuit and inductive cables, may be an overlooked fault or not if it had MOV's.

Conclusion
Don't assume a BMS will protect from this kind of fault.