Telus operates on 850/1900 HSPA frequencies. This is not GSM retro compatible and so you have to ensure the phone from Asia is HSPA compatible. LTE frequency for Telus should be 700 band. So best to research and check the IMEI to see for certain. ...
I think they are roughly like $100-150 everywhere.. maybe ask around at some Telus repair center or something? either that or check to see if any third party locations will repair for cheaper?
Have you tried taking the SIM out and back in and get it to reload the network settings? If that fails, maybe time to give the good guys at TELUS technical service a call?
Yea... $500 is a little steep.. but hopefully over time, it will drop the regular price like the Nexus 4 that dropped to $350.... Sigh... $399 + shipping makes it close to $440 ordering from Google directly.. mmm.....