Code:
driver-btm-c5.c:2990:check_fan_beforeInit: get fan[5] speed=5880
driver-btm-c5.c:3007:check_fan_beforeInit: waiting fans become stable...
edit: replaced the back one too, doesn't even show in network ... driver-btm-c5.c:3007:check_fan_beforeInit: waiting fans become stable...
Sounds like a control board issue to me, of course going with the assumption that the new fan is good, try to use Sdcard the miner using the recovery firmware, if that does not solve it you might need a new control board.