Oh dear god please help me. Let´s try to see here how your brains actually work

- You buy device A from Company B
- You read internets and find out that there is this wonderful app that is for people who like to spend their time in x terminal and run apps from there which need root priviledges.
--After seeing where you struggle I´m not sure if x terminal is for you pal. You could get your N900 really messed up from there.
- Moreover app that you are trying to install is not from Nokia. I´m not sure that if you are aware of this, but you are able to really make your N900 not to boot by installing some apps. And that´s is not Nokias fault. Actually you get warning on default app manager when you install stuff outside of Nokias own app "store"/repository. It´s not there just for fun.

What in the name of god makes you think that Nokia is responsible here.

So let´s try to go on from here
- First check what version of OS you have. You can find your version from settings->about.
- Start x terminal and run command df -h and copy paste output here
.edit So you have done this and it shows that you are using only 57% of space?
-And about that %m error. Well what I think that you have done is that you have not understood wiki.maemo.org flash guide. Probably you have either copied image to wrong directory (should be same with flasher) or you are making typos (remember to use TABulator when giving filenames to flasher).

And please remember that this place is not Nokia support channel. Just mixed group of people trying to do weird kind of stuff with this device.

.edit
Any apps at all. Not even from Nokias own store? Then return it or flash it completely with emmc+rootfs images. Guides can be found from http://wiki.maemo.org