Blurolls kit X or Y axis self-test failed

A batch of Blurolls kits delivered in the first half of 2020 contains X and Y steppers that are slightly out of spec for the Original Prusa firmware.

This results in failing self-tests because the sensorless homing detects steppers blocked although they aren't

Try moving the according axes by hand after disabling the steppers (Menu "Settings --> Disable Steppers"

If the axes can be moved freely manually, try moving them electrically.

Select "Settings --> Move Axis" and then either "Move X" or "Move Y" from the menu.

If the corresponding axis is controllable by this menu, you most likely have to deal with the out-of-spec steppers

Get in touch with Blurolls and claim warranty. They should send you replacement motors.

If you are a little bit on the adventurous side, build yourself a bugfix firmware

Firmware and build instructions are available here on GitHub: Prusa Mini Buddy board firmware

Before building the firmware according to the instructions given at GitHub, modify the file trinamic.cpp located at the ""/src/common"" subdirectory

Look for the code part highlighted in blue in the image and adapt the values for pStep[X_AXIS]->SGTHRS(140) and pStep[Y_AXIS]->SGTHRS(130)

Lowering both values to 110 might give you a good start. Maybe you'll have to retry with even lower values.

After adapting the values, build the firmware according to the Prusa build instructions

To be able to flash the custom firmware, you'll have to physically remove a kind of fuse on the Buddy board, thus voiding your warranty. Again refer to the instructions at GitHub.

This said, we're aware of several blurolls printers that got fixed this way without any further issues.