[Nook HD, HD+ Q&A, Help & Troubleshooting] doltran:
Ran into exactly the same problem.

I had a non-rooted stock HD+, and I decided to give {[Nook HD/HD+][SD Install][4.4] CM11.0 (KitKat) Updated 08/05} a try.

Ironically, I choose this option because it looked like the safest option (I consider myself to have bad luck). I only used the image, ROM, and either micro or nano GAPPS package.

I installed a few random apps from the Play Store like ES Explorer, MX Player, some Cable TV apps, HBO Go, and Chrome. I think Chrome was the only one that I actually used though.

I used it a few days and everything worked just fine. On the day it got borked, the battery was down to around 33% and I plugged it in. It automatically reset and:

- missing /bootdata/BCB (automatically goes into CW recovery if a SD with CW is in)

- can't mount sdcard

- can't mount emmc

[no SD card: the nook doesn't turn on at all when not plugged in to a wall outlet. When plugged in it stays stuck on the black screen with "nook" on it]

[no SD card + plugged into a PC: Doesn't turn on and I can hear the connect/disconnect sound chime over and over...and nothing ever shows up on my PC]

I've looked around, but I couldn't find anything to actually fix this (that I felt competent in trying)...so I haven't tried deleting anything (except the SD card that was in at the time).

So I went once again with the safest option which is:

http://xdaforums.com/showpost.php?p=44790925&postcount=67

The only annoying part is that I couldn't get windows to recognize the nook while it was connect to my PC when in CW recovery (so no adb). Windows and Ubuntu only saw the first small

partition after writing the image file. So I used the backup options within CW recovery and that created the large partition that shows up in Ubuntu. So copy+paste the ROM and gapps in there.

It's now working with this no emmc 10.1 (4.2.2) option. I noticed some error messages with the Play store saying it couldn't download/update some apps (it had auto update turned on). But it works if I download and update

manually.

Oddly enough I had an SD card (PNY class 4 16GB) that wouldn't boot up with the CM11 SD install when my nook was fine. But it boots just fine now that my nook is all messed up. But it runs slow as hell with any ROM. I'm using

a Samsung class 10 and it's night and day difference (the same SD card I had in when my problems started).

There's a website (http://iamafanof.wordpress.com/2014...-4-4-2-for-bricked-no-emmc-nook-hd-02apr2014/) with instructions on how to do a no emmc CM11 install (4.4.2). It worked fine (tested on my slow PNY SD card), but I couldn't get the Play Store to download anything after using the gapps from the CM11 SD install thread....maybe I need a different gapp package. I also just used the ROM that comes on the image. They posted two newer ones, so maybe one of them fix that problem if it's not the gapp package.

So yeah, beware that CM11 4.4 SD install thread!!! It's super simple to try, and it was great while it lasted... But I ran into all these problems just following those simple instructions and not doing anything else...and it didn't last that long either.

If anyone has anything new to add about fixing the mounting issues...I'm all ears. I'm still not really sure if my problem is something that can't be fixed...or if I need to somehow fix files or repartition the emmc.