Note that flashing eMMC will delete the /opt directory, so you *always* need to reflash your rootfs (the COMBINED image) after - or same time as - flashing eMMC (VANILLA img)
When flashing the eMMC content, the safe way is flash the eMMC/VANILLA image first, then remove battery for a moment, and then flash the FIASCO/Rootfs image. Do not boot up the device between the two i.e do NOT use the -R parameter at the end! Also see troubleshooting section, bullet 6:"If you cannot establish..." Rationale: on accidental booting in between the 2 flash processes, the sequence formerly suggested (rootfs first) will result in a broken system. The sequence "eMMC first, then rootfs" is checked back with Nokia affiliates and is proven to work as long as your rootfs still is somewhat functional. Note however that eMMC flashing will fail when your rootfs is completely messed up, the recommended flash sequence then is rootfs, eMMC, rootfs *again*. For users familiar with flashing and interested in a smooth fast process: you can flash combined first, and then *immediately* after that - without one 10th of a second of booting - directly continue with flashing the vanilla. The other way round doesn't work due to a bug in NOLO - so after flashing vanilla you need to remove battery to recover
1. (try to) Turn off the device - if nothing else helps, holding power key for >8s is the ultimate means (except next point 2.) to do this. 2. Remove the battery - even if you were not able to shut device down in 1. 3. Start flasher with above mentioned command to flash (without -R, it's a useless convenience thing). It says "Suitable device not found... waiting" 4. Plug the device to computer with a good USB cable. 5. Insert battery while holding "u" key. You can release the key as soon as screen turns on and shows the USB logo. Flashing shall start automatically. (If flasher answers "unable to enumerate USB buses!" as soon as N900 gets battery, just re-issue same flasher cmd immediately - cursor-up helps ;-D). If flasher doesn't detect the device, a Ctrl+C abort and re-issuing of the flasher command may help