It's difficult to be precise without knowing details of the circuit (layout, and what it is doing) ... but:- MOSFETs tend to fail short circuit. They are also quite sensitive to any over-voltage condition.
So my guess is that the MOSFET substituted is not at the same rating (voltage, especially) as the original ... it fails, after a while as you have mentioned, then zaps the associated resistor when short circuit current flows.
It would be nice if you could establish what the original component values were, and substitute accordingly.
Good Luck!
