Do you still have the old sensor, you may be in luck, you can diagnose by simple ohmic checks with a DVM (Digital Volt Meter).
The "connector" may still be ok, but is the wiring, ok?
This sensor uses a "variable resistor" set up like a divider to check "tension" on the seat belt it's with. IF one of the wires has opened up or is damaged and is shorting out - these conditions cause the voltages the SRS "Expects" - to be out of normal range and sets a trouble code.
You just need to see if voltages are getting to the unit in it's connector, and they can return to the SRS sensor under the main console under the E-Brake handle - if that harness is damaged or not plugged in, there's your reason, just reset/fix the connector and then you can also restore the OEM connector and see if it will clear the code.
Here's a Following up thought to help others...
The issue around "salvage" systems to support other vehicles is a big grey-market area.
Some work, some don't, and many units found in internet sites, are taken off vehicles involved in wrecks, that is why the caution, for many wrecked systems, parts are getting pulled in a salvage yard but what you MAY get is a unit that was damaged in the process and still mechanically work - in protecting the passenger. But may not engage the SRS system correctly and allow the Airbag system to continue to function on that side/sub-system
However, due to the impact that you find from the wrecked system - the possibility that the system that handles the SRS - the electrical side of the unit got poked by the electrical systems failure during the impact, rendering the unit useless for salvage due to the electrical spike in power that SRS and any other system can face in collisions.
So, it may not clear the SRS no matter what you try to use to clear it. Just understand that you may be better off living with the OEM system if it's mechanically working - for it is better than the SRS being numbed by the failure and the squib that launches the side curtain or other airbag system - WONT fire due to the fault it thinks that other system is.