Here you said the homing is to the left rear, but somewhere else you may have said that the Y homing switch is in the front. Which one is it? Which corner does your machine home to (have you witnessed it with the stock board)?
I would recommend the following:
Lower this substantially - perhaps to 9000
Lower to 1000
Lines 44 and 51
Increase both to the max amps of 1.2
That should get you started.
Try jogging around using LightBurn Move Tab.
Use M119 to verify your switches are being read, as explained here: https://lasergods.com/testing-k40-endstops-with-lightburn/
For homing, I still need to know where your switches are actually located and what corner the head moves to to hit them.