first of all check that the image you are trying to flash isn't corrupt , by checking it's md5checksum and comparing it with that on the server .

also,
this can be a battery problem , is it fully charged ? if not , charge it using another phone , or using an external charger and try again , or borrow a fully charged battery from another friend .

I see you have tried to flash the emmc first , this won't work so don't bother , as the phone is required to partially boot before the emmc gets flashed , and since the rootfs is corrupt , it won't boot .

before giving up you may want to try flashing rescue kernel from meego , it will export all the partitions on the n900 as mass storage devices , you may then have a shot at trying to fix them ..