OK i see what you want to do but to flash the emmc you need to also flash the other first but actually i have seen best results on here flashing emmc THEN the fiasco (fw) image after.

The latest vanilla is .....

RX-51_2009SE_10.2010.13-2.VANILLA_PR_EMMC_MR0_ARM.bin

You have to flash both images one after the other either the fiasco then emmc or visa versa and contrary to belief it does not matter which way round you flash.
Just remember NOT to boot your device in between flashing both images ok.

well, i didn't told i want to flash the emmc... i asked if this is the only way i can have the SIM working back again.
and as i mentioned i cannot see the fiasco image in the download page.

to have it understood.
what to your opinion the steps i need to do to have my SIM card working again.
you mentioned i did a mistake and downgraded...how can i upgrade?
with which file? with which kind of file?
how many flash operations i need to go from my current status to working and functioning N900 with SIM working.
please be specific as much as you can.
thank you again for all you help and valuable posts.

And for anyone reading this i will say once again that you CANNOT kill or truly brick the N900 by flashing.
What ever mistakes you make whatever happens the N900 is ALWAYS recoverable with a successful flash no matter what the problems are ie rebooting or what appears to be a dead device that will not boot (the worst scenario lol)

well, i didn't told i want to flash the emmc... i asked if this is the only way i can have the SIM working back again.
and as i mentioned i cannot see the fiasco image in the download page.

to have it understood.
what to your opinion the steps i need to do to have my SIM card working again.
you mentioned i did a mistake and downgraded...how can i upgrade?
with which file? with which kind of file?
how many flash operations i need to go from my current status to working and functioning N900 with SIM working.
please be specific as much as you can.
thank you again for all you help and valuable posts.

just a thought - can i use right now the Nokia software updater to upgrade after i downgraded?

2 ways you can cure this.... flash both images using the downgraded fiasco with the emmc image or... flash the latest global or fiasco for your part of the world (as i don't know where you are i cannot tell you the exact image for your area).
The latest GLOBAL fiasco image is...

RX-51_2009SE_10.2010.19-1_PR_COMBINED_MR0_ARM.bin

Run the way your going no need to complicate things lol and besides NSU is damm slow sometimes lol.

Yes you can use NSU now you downgraded.