Make sure the clip is on good, then flash your original bios again. With first switch up and the rest down.
If your clip is on good enough, after flashing your original bios, reboot the PS3 with all switches down.
Your PS3 should then be restored to before you tried to downgrade.
I believe the flashing process didn't work, because your clip wasn't connected good enough. So what it reads for your metldr is not correct.
EDIT - Also, are you sure your backup is good? Did you validate it? Maybe upload it here so, someone can check it.