【有悬赏】【写字机器人】步进电机不动

Question

写字机器人不动
这是我自己做的一个写字机器人，固件是GRBL1.1用的Uno+CNC雕刻版+A4988
我一直用的好好的，结果今天出了问题,问题如下：

1. x轴步进电机不转，但电机是好的
2. y轴步进电机不转，但电机是好的

我尝试接了一个新的电机，也不动，但z轴可以正常使用。在复位键按下后会电机动一下，但动完电机的轴就没力气一样（正常电机的轴是很有力的，很硬很硬，基本用手转不动），软件也控制不了，就是不动，A4988也没有温度。A4988换过了，CNC雕刻板也换过了，uno也换过了。电一直是用的24V，之前都没问题。
昨天还是可以动的，但连接不上，所以我重刷了固件：

/***********************************************************************
This sketch compiles and uploads Grbl to your 328p-based Arduino! 

To use:
- First make sure you have imported Grbl source code into your Arduino
  IDE. There are details on our Github website on how to do this.

- Select your Arduino Board and Serial Port in the Tools drop-down menu.
  NOTE: Grbl only officially supports 328p-based Arduinos, like the Uno.
  Using other boards will likely not work!

- Then just click 'Upload'. That's it!

For advanced users:
  If you'd like to see what else Grbl can do, there are some additional
  options for customization and features you can enable or disable. 
  Navigate your file system to where the Arduino IDE has stored the Grbl 
  source code files, open the 'config.h' file in your favorite text 
  editor. Inside are dozens of feature descriptions and #defines. Simply
  comment or uncomment the #defines or alter their assigned values, save
  your changes, and then click 'Upload' here. 

Copyright (c) 2015 Sungeun K. Jeon
Released under the MIT-license. See license.txt for details.
***********************************************************************/

#include <grbl.h>

// Do not alter this file!

感谢各位！如果你的办法我经过尝试有效，我会通过打赏的方式打赏1-10元不等(因为直接设置悬赏要在7天内采纳，并且至少悬赏15元)。