I know this model was made for Nextel, but does anyone know if it's
possible to use a T-Mobile sim card with it?

Short version - I live in NC (no T-Mobile here) and ruined my "old"
blackberry with a short dip in the washing machine.  I have a 7520 here
but cannot get it to read my T-Mobile card.  I get no error message
saying the card is bad or anything like that.  I have completely wiped
it.

Any suggestions?