I have backup 20180914, only difference vs 20180926 is miner executable. Above 0926 is different linux distro. I might upload somewhere tomorrow if you wish, but on earlier pages was link to that if i remember

edit:
here is earlier firmware
core update = ver. 20180914 (image file)
upgrade file = ver. 20180926 (update zip from miner web)
https://drive.google.com/drive/folders/1peQyWr55ddLdDq5jaU_jSShlEY4y_hqY