Nexus One won't accept OTA updates

[mrozema]

Hello all,
Perhaps someone out there can help me with my Nexus One. The regular OTA updates fail every time with an invalid signature error.
I bought the phone second hand and am now suspecting that the phone might have been rooted.

Can someone tell me how to tell if my phone is rooted? And then how I can restore it to a point where it will accept the OTA updates?

Thanks!
Matt.

[Lee Yuan Sheng]

Look for Superuser and install it, then install Terminal Emulator. Run Terminal, type "su", hit enter, and see if Superuser pops up.

Depending on how technical you are, you can consider installing a custom ROM on the Nexus One. The community behind it is strong, so the ROMs are of good quality.