I started up 2 S9 13.5s this week and seemed fine until I added the worker names. After the reboot, the green light went solid. Bminer was blank and firmware too. Pulled my hair out for a couple hours rebooting, updating firmware etc. I gave up for the night and they were both hashing fine when I checked in the morning and have been running since. I had a similar issue with my 14.0. I don't know if it's the newer batches but something happens when you change the worker name. My L3+ connects instantly but not the S9s. Hope that helps.