Okay. If you do find that X isn't starting and that /osh is empty, get a root terminal somehow (using adb, if it works, or Android Terminal Emulator, if it doesn't) and do the following:
- First, make sure that /system/bin/mountosh.orig is there: ls /system/bin/mountosh.orig
- Move the original mountosh back: mv /system/bin/mountosh.orig /system/bin/mountosh
- Reboot: reboot
After these steps, you should be back to using the stock Ubuntu installation.
I can't find a free loopback device?
# /sbin/losetup /dev/block/loop7
/sbin/losetup /dev/block/loop7
/dev/block/loop7: [b312]:26 (c220b83ae2fef0c024d6aaaedc1372dd)
# /sbin/losetup /dev/block/loop6
/sbin/losetup /dev/block/loop6
/dev/block/loop6: [b312]:22 (f282eaf309aab3c58a4812ab76812126)
# /sbin/losetup /dev/block/loop5
/sbin/losetup /dev/block/loop5
/dev/block/loop5: [b312]:25 (d6ff19a29138895404662d7dff7bfd7a)
# /sbin/losetup /dev/block/loop4
/sbin/losetup /dev/block/loop4
/dev/block/loop4: [b312]:28 (c563c01fe809a053d5801c99e55ac8cf)
# /sbin/losetup /dev/block/loop3
/sbin/losetup /dev/block/loop3
/dev/block/loop3: [b312]:29 (f9672f198e589a02c9d738b01516be84)
# /sbin/losetup /dev/block/loop2
/sbin/losetup /dev/block/loop2
/dev/block/loop2: [b312]:27 (7b437dd3fc4c166018ac49cc9006a01d)
# /sbin/losetup /dev/block/loop1
/sbin/losetup /dev/block/loop1
/dev/block/loop1: [b312]:23 (088ffe4aba111a31f89de6ddb1eb1be2)
# /sbin/losetup /dev/block/loop0
/sbin/losetup /dev/block/loop0
/dev/block/loop0: [b312]:30 (b21057058a9b2e446ee1175dd53b2c67)