Can't mount first-gen Kindle Fire in TWRP I have a rooted Kindle Fire running TWRP that I let my kids use. Last week the battery ran low and it shut off, but my three-year-old son somehow booted it into TWRP and wiped the device. Now the Fire hangs at the Kindle logo during boot.

TWRP still works, and I've attempted to mount /sdcard in order to upload cyanogenmod. Strangely, the Kindle is not talking to my Ubuntu PC: when I plug it in, lsusb reports no additional devices and dmesg reports that the device is disconnecting almost immediately:

[450654.465431] usb 1-4.7.2: &gt;new high-speed USB device number 14 using ehci_hcd
[450654.558614] usb 1-4.7.2: &gt;New USB device found, idVendor=18d1, idProduct=0100
[450654.558622] usb 1-4.7.2: &gt;New USB device strings: Mfr=5, Product=1, SerialNumber=2
[450654.558627] usb 1-4.7.2: &gt;Product: kindle
[450654.558631] usb 1-4.7.2: &gt;Manufacturer: Amazon
[450654.558634] usb 1-4.7.2: &gt;SerialNumber: 0123456789ABCDEF
[450657.586116] usb 1-4.7.2: &gt;USB disconnect, device number 14


I'm at a loss for how to diagnose this further. The fk/FireKit tools can access the device but only while it's booting up, and despite using fk to reflash TWRP I have noticed no improvement. 

Edit: As my answer indicates, I solved the problem by unbricking the Kindle with a different computer. This shouldn't have helped. I'm still very open to any answer that helps to identify the real issue.
Ultimately I plugged the Kindle into my Macbook instead of my Ubuntu machine, and it mounted it just fine. No idea what the issue is with my desktop - all other devices on the hub work fine, switching ports changed nothing, etc etc.

If your device won't mount, try it with a different computer. For some reason.