Hi,
I’ve downloaded today the following image file: bone-debian-8.0-lxqt-4gb-armhf-2015-05-04-4gb.img to an SD card.
My BBB is an A5C with 2GB eMMC.
BBB booted correctly with HDMI display and was working fine.
Then I’ve connected my 4D system LCD cape 70T. Nothing was displayed.
So I’ve googled a bit and found that adding dtb=am335x-boneblack-4dcape-70t.dtb to /boot/uEnv.txt will activate the display.
I’ve edited the uEnv.txt file and rebooted.
That was the last time I saw my BBB alive 
When powering up, the power led flashes for a sub-second and nothing happens after that. Pressing the power button will repeat the phenomena.
Question:
Is it possible to destroy a BBB just by changing a line in uEnv.txt? could somehow one of the GPIO lines was shortened due to bad configuration?
I don’t want to destroy my next BBB doing the same thing that could have destroyed my first…
Yoram