As jhowell said, that Kindle has a corrupted eMMC flash chip. See
https://www.mobileread.com/forums/sho....php?p=2810749 for more details.
If it makes you feel any better, you got tripped up by a very rare bug.
When your mother said it was in perfect working order, she clearly didn't know what she was talking about
because that Kindle has permanent, catastrophic hardware damage.
...
You could fix it... if you have the parts from another (broken) Kindle Touch. Alternatively, there are probably places you can get an eMMC chip that will fit in the Kindle.
But that kind of hardware repair is beyond the skills of many people.