I just went through this. How I got it to finally install correctly is the sd card method for board recovery that is posted in the thread. boot up from sd card. remove sdcard while it is on. Flash through web interface with the old L3 (not the + version) firmware that is on the bitmain website. (Antminer-L3-201704271449-384M.tar.gz)
Then flash the bliss firmware and it will work.
According to
blissfirmware official thread it won't work if you flash the L3+ with non plus firmware.
Bitmain removed the other firmware from their download page for l3+ so I think the board recovery is enough for L3+ just make sure after successfully flash the miner with SD card image fully factory reset the miner by holding the IP reporter/reset button for 15 seconds.
After factory reset, you can flash it with blissz firmware through web interface.
This method should work.