Ok, I just re-did the SD install of Android build #99 (Lollipop 5.1.1).
I did not flash the latest Android build #118---it failed when I did it the first time.
I see none of the LEDs come on when Android boots.
Note: it takes a little less than a minute for Qualcomm's logo to appear, then it goes black, then about 2 minutes later, the Android screen pops up.
Then that will go back to black in a minute if there is no mouse/keyboard input---Android screensaver set to 1-minute timeout.
The blue LED only comes on when I turn on the Bluetooth--a steady blue, not blinking even when scanning for other BT devices.
You might want to try an SD card install of Android or Debian (at least it blinks a LED).
Or drop it into fastboot mode and see if you the fastboot tool "sees" something.
Just note: I ran into a problem when I re-used the uSD card I had used to do an SD image install of Debian. Even though I re-flashed it with an SD Android image, when I put it in the DB410C it said it was re-flashing Debian again. I did it twice, making sure I picked the right image and checking the write protect on my SD adapter carrier was off.
I eventually did a 'dd if=/dev/zero of=/dev/mmcblk0 oflag=sync bs=1G count=8' to zero it out.
Re-flashed SD Android image onto it again, that finally worked. Weird.