The factory reset should usually always work unless there is a problem with the card itself, or you installed an incompatible kernel/update manually, or the recovery partition was corrupted somehow...
If nothing else helps, you can access the microsd card directly. The back of the Libra 2 pops off (with care - the display cracks easily), the microsd card itself is "glued" in, my removal experience
here and
here, basically I glued a strip of paper onto the card itself and pulled it out with that - after alcohol alone didn't help.
Once you got the card, you can attempt to make an image of it (with ddrescue) and see if it works with a new card. If you have a Linux system available, you can also format the user partition there, and then see if a factory reset will work afterwards. (Depends on what is causing the boot loop).
If your card is dead, try the
image request thread. Note there are different hardware revisions of the Libra 2.