Thanks for the reply..
The normal boot failed with
 failed to get ffbm cookie use_signed_kernel=0, is_unlocked=0, is_tampered=0.
 Loading boot image (14020608): start
 Loading boot image (14020608): done
 DTB Total entry: 15, DTB version: 2
 Using DTB entry 0x000000f7/00000000/0x00010018/0 for device 0x000000f7/00010000/0x00010018/0
 Using pmic info 0x2000b/0x0/0x0/0x0 for device 0x2000b/0x0/0x0/0x0
 target_display_panel_node:510: hw_id=24 panel_name="qcom,cc-debug-8936"
 cmdline: root=/dev/mmcblk0p10 rw rootwait console=ttyMSM0,115200n8 androidboot.emmc=true androidboot.serialno=b94c1d70 androidboot.baseband=apq adv7533_dsi2hdmi.panel=dsi mdss_mdp.panel=1:dsi:0:qcom,mdss_dsi_qcom,cc-debug-8936
 Updating device tree: start
 Updating device tree: done
 booting linux @ 0x80080000, ramdisk @ 0x82000000 (2770953), tags/device tree @ 0x81e00000
 Jumping to kernel via monitor
<< HANG >>
When attempting to enable fastboot mode (which I had already done - successfully - several times before..) the system hung, before the 'reset / fastboot: processing commands' messages.. I did check the switch settings etc... and retried several times..
According to the documentation, the rescue sd process is supposed to produce a message similar to
Rescue image for DragonBoard 410c, boot into fastboot mode only
fastboot: processing commands
- and what I was seeing on the console did not match this..
After your comment that fastboot probably had installed, I tried booting into fastboot mode again, and this time it did work..
Many thanks for your assistance.. Maybe the documentation needs to be updated..!
July 1, 2015