Please thank lj50036 from the CMB team.
It was him that guided me thru the process to unbrick my TP.
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Bricked situation:
1. Last activity before brick: Stock with latest OTA -> Flatline (OK) -> Motochopper (OK) -> Flash CWM recovery (OK) -> Unofficial CM11 (Reboot = bricked)
2. Stuck at ASUS logo on power up/reboot. (Device is unlocked no longer shows on top left corner)
3. Cannot get to fastboot (power + dwn = stuck at ASUS logo)
4. However, can invoke APX mode (power + up = APX device detects in windows)
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Preparation:
1. All the output files from the flatline (blob.bin, unlock-token, bricksafe, factory-config etc)
2. Fastboot,adb,nvflash exe (you should have all these when you did flatline)
3. Enough battery (I left it overnight to charge, since I had no way of checking batt)
4. The stock firmware from ASUS (you should get the same version as the one you had prior to brick)
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Actual process:
1. I was told to put all the files from fastboot,nvflash etc in C root (ie .exe,.img,.dlls, bin etc). I think it is not a must, as long as you have all the files together and dir has no spaces.
2. Unzip the firmware file from ASUS.
My case: the file name is JP_epaduser_10_4_2_18UpdateLauncher, extracted to find JP_epad-user-10.4.2.18. Extract again to find a file called Blob, which is about 500mb.
3. Copy the blob file to C root
4. Open CMD as admin. Make sure you do so as admin.
5. Goto C root, type: cd\
6. Just make sure you can execute the following exe: fastboot, adb, nvflash, type: fastboot
The commands should output the help related info....ie parameters etc
7. Now boot you tablet into apx conneted to your pc from tablet to pc no hubs docks> Device manager shows Asus tranformer prime APX interface.
8. Type: wheelie --blob blob.bin
My output:
C:\>wheelie --blob blob.bin
Wheelie 0.1 - Preflight for nvflash.
Copyright (c) 2011-2012 androidroot.mobi
========================================
Waiting for device in APX mode...
[=] Chip UID: 0x15c7d7a49042111
[=] RCM Version: 0x30001
[=] CPU Model: Tegra 3
[+] Sending bootloader...
Sending file: 100 %
[!] Done - your device should now be ready for nvflash
My tablet screen shows:
top left: entering nvflash recovering mode / nv3p server
chip uid: 015c7d7a49042111
center: Asus
bottom right

owr by...
9. Now it may reboot at the end of this just get back to apx mode on your tablet.
Type: nvflash -r --download 7 unlock-token.img
Output:
C:\>nvflash -r --download 7 unlock-token.img
Nvflash v1.13.87205 started
[resume mode]
sending file: unlock-token.img
unlock-token.img sent successfully
*My device black out. So i rebooted to APX again as instructed.
10. Type: wheelie --blob blob.bin
11. Type: nvflash -r --download 14 factory-config.img
Output:
C:\>nvflash -r --download 14 factory-config.img
Nvflash v1.13.87205 started
[resume mode]
sending file: factory-config.img
factory-config.img sent successfully
*My device black out. So i rebooted to APX again as instructed. An did wheelie again
12. Type: nvflash -r --rawdevicewrite 0 2944 bricksafe.img
Output:
C:\>nvflash -r --rawdevicewrite 0 2944 bricksafe.img
Nvflash v1.13.87205 started
[resume mode]
sending file: bricksafe.img
bricksafe.img sent successfully
*device did not blackout this time. So no need to reboot.
13. Type: nvflash -r --go
Output:
C:\>nvflash -r --go
Nvflash v1.13.87205 started
[resume mode]
14. Power + DWN to try to get to fastboot. Select the USB icon.
*windows device manager should detect fast boot interface
*confirm this by typing: fastboot devices
*my output was: 015c7d7a49042111 fastboot
15. Type: fastboot erase system
Output:
C:\>fastboot erase system
******** Did you mean to fastboot format this partition?
erasing 'system'...
OKAY [ 2.671s]
finished. total time: 2.671s
16. Type: fastboot erase recovery
Output:
C:\>fastboot erase recovery
erasing 'recovery'...
OKAY [ 1.929s]
finished. total time: 1.929s
17. Type: fastboot -w
Output:
C:\>fastboot -w
erasing 'userdata'...
OKAY [ 50.110s]
formatting 'userdata' partition...
Creating filesystem with parameters:
Size: 61980278784
Block size: 4096
Blocks per group: 32768
Inodes per group: 8192
Inode size: 256
Journal blocks: 32768
Label:
Blocks: 15131904
Block groups: 462
Reserved block group size: 1024
Created filesystem with 11/3784704 inodes and 283616/15131904 blocks
sending 'userdata' (141195 KB)...
Created filesystem with 11/3784704 inodes and 283616/15131904 blocks
sending 'userdata' (141195 KB)...
writing 'userdata'...
OKAY [ 26.179s]
FAILED (command write failed (Unknown error))
finished. total time: 76.878s
*dont be bothered by the error
18. Type: fastboot devices
Output:
C:\>fastboot devices
???????????? fastboot
19. Reboot and get back to fastboot again, check that your device is detected by Type: fastboot devices
Output:
C:\>fastboot devices
015c7d7a49042111 fastboot
20.fastboot erase boot
Output:
C:\>fastboot erase boot
erasing 'boot'...
OKAY [ 1.874s]
finished. total time: 1.874s
21.Type: fastboot erase misc
Output:
C:\>fastboot erase misc
erasing 'misc'...
OKAY [ 0.978s]
finished. total time: 0.978s
22. Type: fastboot erase cache
Output:
C:\>fastboot erase cache
******** Did you mean to fastboot format this partition?
erasing 'cache'...
OKAY [ 1.713s]
finished. total time: 1.713s
23. Next cmd takes long time. Type: fastboot -i 0x0B05 flash system blob
* During the writing process of this step you will get the blue bar on your screen.....
Output:
C:\>fastboot -i 0x0B05 flash system blob
erasing 'system'...
OKAY [ 2.225s]
sending 'system' (537604 KB)...
OKAY [ 90.363s]
writing 'system'...
OKAY [130.010s]
finished. total time: 222.600s
24. Type: fastboot -i 0x0B05 reboot
*this reboot should bring you to stock rom
*will take some time, just be patient
*does not matter if you have usb connected or not
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If you reach here, you should have a fresh TP with stock, except its unlocked.
Hope this helps.