N80 "Phone start up failed"

Install New Software Through Nokia Ovi Suite connect Phone with data cable and install software..

Try this:

1. In offline mode *#7370#
2. Restart
3. Enter city/time/date etc.
4. Plug phone into charger
5. Change network to automatic
6. Activate pager profile
7. Turn off phone
8. Turn on phone
9. Change profile to general

hi :) 12345 is nokia original lock code. if u mean sim lock,here have a web for u maybe useful. www.unlock-zone.com

Try this, it might work for you. First remove any extra memory card and sim card inside your phone. After doing that, turn on your phone without those things. If there is message "Please insert sim card" then your good to go. Put your sim card back to your phone and then turn it on again. If it is successfully start then next thing to do is to insert the memory card back to your phone and then start up your phone again. But if in this stage your phone failed to start, then the memory card it causing the problem.
If all fails, then you need to format or hard reset your phone. Hold the * + 3 + green call key and then start up your phone while holding those buttons until you see a screen that shows formatting. Make sure you have enough battery power to do this procedure. You can plug the phone charger to make sure that everything will be okay.

Please leave comments for further instructions. Thanks..

Maybe its your battery or charger port.Try to use another battery, if did'nt work then it's charger port.To avoid this kind of error please do not overcharged your phone.

Sounds like the connection between the phone and the battery may have gotten corroded or dirty. Another possibility: Something is the matter with your charger. Go to a Nokia outlet and see if they can charge your battery. If they cant, they need to fix your phone.

System might be damanged,

You can hard reset the phone (Factory Settings)
This will reinstall the operating system inside the phone back to how it first was.
(internal memory gets formatted then the rom reloads the os back)
(Solves all kinds of problems.)

Switch the phone "OFF"
Hold "3" (button) + "Green Call" (button) + "*" (star button)
Switch the phone "ON" while holding the above three buttons.
Continue holding for about 20 seconds then let go.

Please note this will format all the saved information stored in phone memory. including phonebook numbers (if not stored on SIM card).
Try to make backups first.
You have been "Warned".

Best of Luck.

Try to do a hard reset!

The method of performing a hard-format, i.e resetting it completely to factory defaults and removing all data, is as follows:

1. Switch off the phone.
2. Hold down the following three buttons: Green (call answer) button, * button, and '3' button
3. While holding these buttons, press the power button and switch on the phone
4. When the message 'Formatting' appears on the screen, release all of the buttons

Note that you shouldn't switch the phone off or remove the battery when performing either of these operations, and it's advised that the handset has a reasonable amount of battery charge before performing a format/reset. As data will be lost, you are advised to perform a backup first.

If this method doesn't work you probably will need to go to a Nokia Service Centre and have your phone flashed!

try removing the battery, removing the sim, plug in the charger -> try turn on. Insert battery (no sim), plug charger -> try turn on Remove charger -> try turn on Insert sim/battery/charger -> try turn on.