*ALREADY FIXED*
Never set snap to grid to 0 in transitions.ini, either with Theme Customizer or any other way
If you do, you'll find yourself into a big headache


I do realise that flashing fixes my issue, but...


I was using my N900 some days ago, and decided it was time to change my icons. Went on Theme Customizer and i changed the icons, Desktop Grid (Snap to grid, or something) to 0. After i applied the settings, it stuck on Restarting services. It was restarting hildon desktop (which makes those black things and blinks the screen). Then the NOKIA logo appeared and i was "Oh what the..."

It went on a infinite boot loop.
Both on power kernel and the stock one ( i got multiboot and nitdroid 0.0.8).
It loads, the dots appear, then it asks for the PIN code, i enter it (or just skip, it reboots anyways) then it shows the boot video. After the boot video, it loads part of the hildon.
It shows the menu button and background, but it doesn't shows the battery icon, hours, etc.
After you wait a little, the screen blinks as if it was restarting hildon-desktop and hildon-home (did i misspeled some of them?) and i can notice that all the widgets (web bookmarks) appears on the upper left corner of the phone, below the menu button.
After some "blinks" the NOKIA logo shows up again and you know the story: infinite boot loop.
NITDroid works fine (obviously, as the problem must be something related with Theme Customizer actions).
I will try reflashing rootFS only, but right now i don't have my laptop (which is running Ubuntu Lucid Lynx) and my desktop PC (which i am using now) has Windows 7 x64.

My question is, is there a way to "fix" the problem without reflashing
or at least, backing up my contacts and stuff? I can't access the mass storage with the PC. :\

I've been searching in the wiki, and I've seen the guide to reflash, etc. And I know i should have made a backup of the phone. I acted like a noob (maybe I am a noob)

As far as I know, contacts and most of the stuff won't be lost if you just reflash the Fiasco image. None of your problem should be in the eMMC. However, this makes me think that it may be useful to write a program in Java/Dalvik for use on NITDroid, to allow access to the Maemo filesystem from within NITDroid... Don't know if it already exists, or it the way NITDroid is ported permits for it, but it seems like it should be doable enough.

There's also a 'recovery' kernel available on meego.org, which allows for booting into some sort of shell with access to the file system, I THINK. Don't quote me on that, I don't remember much, since it's only come up once in the threads I was looking at.

In the future, since you're using Multiboot, install BackupMenu. It makes much better backups than the default backup application (namely, just makes .tar archives of the filesystem, so you can unpack that entire thing and voila. Last I checked. It may have changed since then).

It also means that if you can boot to Bootmenu, you can launch BackupMenu, thus getting the access to the file system you'd need in a case like this.

Anyway, at this stage, just go for the fiasco reflash. Hildon-Desktop is above the kernel, so just kernel-only reflashing won't fix it AFAIK. However, the Fiasco image reflash won't touch any of the stuff on your Mass Storage area, just the rootfs and optfs, I think (and you may be able to selectively flash just the RootFS image... You may have to first unpack the latest Fiasco image with the same flasher utility, and use the RootFS image itself. However, whenever I flash just kernel, the -k option works on the Fiasco image, so it should be able to read the rootfs image from inside the Fiasco image just as well as it can read the kernel image from within the Fiasco image.

Use R&D mode and set the RD flag no-lifeguard-reset
Basically:
This should kill the watchdog, and you should be able to boot up fine and reverse the changes.

Ok, thanks for the (kinda) fast answers. Will try later as right now i have to sleep (didn't slept this night). Flashing a phone while half-asleep surely doesn't gives you nice results

It's not exactly flashing, it only sets a flag in CAL

Managed to get some time and now the device is in R&D mode and disabled lifeguard like you said. No more boot loop.

Hildon-Home seems to be the main problem - because hildon desktop loads fine (not the status bar icons, etc.)
Managed to kill hildon-home and load hildon-desktop - it loaded fine.
But hildon-home goes back in 1sec and bam, it messes the whole stuff again.

Ehm, probably the only way out is flashing rootFS

Or a way to replace bugged/ hildon-home without flashing rootFS, but i'm not sure how to do it

It would appear that it's time to flash the rootfs

http://wiki.maemo.org/Updating_the_firmware

Yeah, indeed. I will do it, it is better than having a half-raped phone.

setting the snap to grid to 0 bricks the phone
change it to something else (if you can right now, that is)

Oh, fail. Then that's the problem, i can edit it! I was about to flash the rootFS right now, lol.