AT&T 920 main board replacement?

[nitrocs]

I upgraded from my day 1 L920 to a L1520 recently & had used a sim adapter in the 920 for one day while configuring my new phone. I left the empty adapter in the phone & went to give the phone to another family member to try out WP, but the sim tray was stuck! Of course I gorilla'd it...and now the phone wont recognize any sims that are inserted. Seems as though I destroyed the sim reader pins, so I ordered a replacement "main PCB board" from a seller on eBay, but am now worrying if it will be compatible. Are there any main board differences between the RM-820 (at&t 920) and the RM-821?

Any advice on a course of action if the board I ordered will not work? I'd budget $100-$150 to fix the phone but any more & I could retire it to xbox ONE remote usage.