3G forum is reporting that a new firmware v 2.00.052 is available for Nokia N91 through the Nokia Software update utility. But users have had problems if the HDD is not formatted before installing the firmware upgrade.

Here’s a step by step on how to upgrade your Nokia N91’s firmware:

1) Make sure you have the latest PC suite (6.81)from : http://europe.nokia.com/A4144903, or other local regional sites.

2) Install the Nokia software update application sw from http://www.nokia.co.uk/softwareupdate (note you need 256MBytes of RAM on your PC)

3) Then program your phone

a) Backup your phone memory (ROM) using PC suite (to preserve your DRM activation keys etc).

b) Copy your files (Music, Videos, Documents, Images etc) from the device HDD to your PC (recommended to use USB Mass storage).

c) Copy your applications, themes etc (original SISX, Java etc files before you installed them) from your HDD to your PC (Do not simply copy the installed directories/files over)

d) FORMAT your HDD

e) Proceed with SW update (note you need to be attached to a charger and not in offline mode. Do not answer or make call or disconnect the device during this process)

f) Reset your phone memory by typing *#7370# (code 12345) (recommend this just to be safe)

g) Restore your phone memory using PC suite

h) Copy back your HDD contents from your PC to your clean HDD

h) Re-install your applications/themes

Thanks to music101 over at the 3G forum.