No need for ssh as long as 'rootsh' is installed (do not think so) or it is installable (depends on dependencies to old Nokia servers, but even ghat is solvable). There is even a dedicated thread for peeps like you (sorry, no time gor spoonfeeding).
So try rootsh or Nokia application manager and try to install rootsh. Hopefully you know the so called "command line"?

True.
I also mix up if PR1.3 enabled or disabled flashing over the device code (a proper search will revealbthe truth. think joergrw was 'involved'j.

Re-read edit:
it is definitely not the.FIASCO image but the.eMMC image so all data would be gone.

Hi, yes it is my phone. Got it new as a present from my dad years ago and loved from the first moment. Love the fm transmitter and infrared port even though nowadays that is pretty useless but it is still good to have it. This phone had a 3.5 mms jack when Apple didn't. Same for Bluetooth. The keyboard is great and the stereo speakers the same. The camera is old for today's standards but still is a great piece of engineering. I have a Samsung S7 edge today and have no intention to use the N900 as day phone but would like to store it and keep it safe fully functional, not locked. I live now in DUBLIN but this phone has a Spanish keyboard because I'm Spanish and got it there.
Any advice about what d be the best option?

In principle everybody could find the information because it is already posted here.
So I will give you some hints.

Method 1: Resetting the code with rescue os. Boot with the flasher the rescue os and type.

This will reset your code to the default one "12345".

Method 2: Figure out the typed in code. Boot with the flasher the rescure os and grep the encrypted code from mtd1 and use john the ripper to brute force the code. Wondering what kind of stupid code you chosen in the past and type it in after rebooting the device. Remember the code or change it.

You could use for both methods my rescue live image, so you don't need to install the flasher and don't need to download rescue os because it is on board.

Thanks Halftux

I'd say the rescueOS way is to go; I have myself used that to revive old devices and it is pretty straightforward thing to do.

As for going to a repair shop and leaving it for "Experts" to sort out... I would definitely recommend against that.
There are no repair shops in existence today that have the knowledge to do anything at all to a N900 so for the technician to do anything useful would first come here and ask about it from TMO
This means it would be a training opportunity for the technician that you'd need to pay for!

Thanks juiceme

Hi, does anybody know why after downloading the flasher 3.5 for Windows and installing it, it doesn't open? I tried on a Windows 8 with compatibility for older software and also on another laptop with Windows xp and nothing, it doesn't load. It just pop up a black screen with some text in white characters for 1 second and then is gone. What am I doing wrong?

I think I could get it sorted if I can get the flasher

Flasher is a command line utility. You do not really install it, you just copy it to a chosen directory ("folder" in Microsoft speak) and launch it from the command line.

Other reasons for not working might be:
- using a 64-bit version of Windows (runs on 32 bits only)
- using a version of Windows newer than 7
- missing drivers

For the last one, installing Nokia PC Suite 3.8 may help. Google for it, it can still be found lying around.

For the other two, find an older PC with a 32-bit version of Windows 7.

Alternatively, download a Linux version of flasher and a live Debian or Ubuntu CD (must be 32 bits, but otherwise the version does not matter) and try this way.