The behavior you describe is consistent with the Z-Min endstop being falsely triggered. To verify that is the case:
- Start the printer
- Home printhead and bed
- Manually move the printhead and bed away from endstops.
- Open the console window and send an M119 command.
The printer’s reply to M119 will show which endstops are “open” and which are “triggered”. With the bed and toolhead away from all endstops, they SHOULD all be “open”. If instead there are multiple endstops in the triggered state, it is likely your mini-Rambo board is blown and needs to be replaced (false triggering could be caused by bad switches or wiring, but it is unlikely for (2) or more of those to fail at once). If only the Z_Min is triggered, then I would definitely proceed to check wiring first, but it may still be the Rambo board.
There are several threads on the forum that go into more detail on this exact problem. Here is a fairly recent one:
https://forum.lulzbot.com/t/endstop-triggering-on-lulzbot-mini/5490/8
If the M119 shows all endstops “open”, then something else is amiss…