Hi!

I bought a nexus one in the USA. The nexus one is NOT unlocked. (No small padlock shown while booting).
The nexus one is NOT rooted. (Terminal Emulator : basically everything -> permission denied)

Every now and then I get a dialog that tells me that there is a new system upgrade available. When I try to upgrade my system, after a reboot, i get the following:

Code:
Android system recovery

reboot, etc.

Build : RA-nexus-v1.5.3
Finding update package...
Opening update package...
Verifying update package...
E:No signature (8 files)
E:Verification failed
Installation aborted.
Android version is 2.2
Baseband version is 32.36.00.28U_4.06.00.12_7
Kernel version is : 2.6.32.9-27227-g3c98b0d android-build@apa26 #1
Build number is : FRF91

How can I install the system update?