Ok, thanks guys. I’m still waiting to hear back from support, but at least now I have a place to start.
So I checked out the three fuses on the board and they all check out ok. So I’m guessing the board is the culprit…
And wouldn’t you know it, tech support is closed today for weather. 
Anyone know why the lulzbot store does not have the Rambo board listed for the Mini?
Hello Everyone,
I just want to pop in here and put a quick warning about cleaning your Mini nozzle with a wire brush.
If you use a wire brush to clean the nozzle on your Mini you will more then likely blow the rambo. The voltage used for bed leveling that is attached to the nozzle will short when a brush is used for cleaning. Thus leaving the rambo useless. This will fry the stepper driver almost instantly.
Please don’t use a wire brush on the Mini nozzle!
Wish I read this earlier! So I used a wire brush and now the z axis won’t move. What do I do now to fix it? Thank you.
I replaced a bad thermistor in my Mini and now have the same issue. I am assuming now after reading this thread that I must have unintentionally shorted my board. If anyone has another possible solution besides dropping $200 on a new board, please let me know.
Measure to make sure you do not have one of the two thermistor leads touching the heat block. If it is it will cause end stop issues also.
Just started having this problem (z-axis only) after taking apart my extruder assembly. I’m trying to print my own replacement fan thingy to reduce heat creep. I did not use a wire brush on mine and mine also thinks that the lower endstop is hit (when the upper home switch is pressed), but if i can get it “unstuck” from that switch my z-axis works fine. Homing was weird because it either cleans in the air and skips homing or it went down and touched the first washer, but the remaining 3 washers the z-axis went the wrong direction! The last time i had weird print issues and strange geometry it was because my motors did not have the ferrite torroids on them to prevent electrical noise. So my first instinct was to look for wiring problems (as apposed to a bad board, although anything is possible).
Considering my extruder wiring was flailing around just before this issue started and that the problem was temporarily fixed by moving those wires around the most likely cause is a wiring problem. i will assume at this point my thermistor may be shorting out to the heater assembly and causing strange behavior. So i will check that as soon as possible. Thanks for the tip.
Yup, that seems to have been the problem. fiddled with resetting the thermistor with the plastic tubing as to not short out to the hot end and the printer is now back up to normal printing.
I get a problem periodically where after the bed levelling procedure fails, the z motors look like they’re spinning the z axis threaded rods, but the head doesn’t move.
Usually fiddling with things, resetting Octopi/ Octoprint along with the printer a few times and fiddling with the controls in Octoprint like “motors off” and it’ll start homing again soon after.
I don’t know exactly what is happening or why fiddling with it fixes it, but it seems to work. I do go through a period where the controls in Octoprint are pretty unresponsive, though.