Its probably just firmware.
You can't use a lcd for much in the way diagnosis. Its designed for a working machine.
Connect up a pc, install printrun/pronterface and connect to the printer over USB
Firstly test your endstops.
Make sure no endstops are being hit
Sending the machine M119 (display endstop status) It should report all open
Next with a finger hold down a endstop and send M119 again. Verify the endstop your holding down now says Triggered.
Repeat for all endstops.
Fix any issues found.
Next test homing direction
With your hand at the ready near the X endstop, home the X axis, check it moves towards the endstop on that axis,
if it does, let it do its thing. If it moves away, Hold down the endstop. It should stop moving
repeat for Y and Z axis (With Z it probably best to manually hold the endstop regardless, stop it hitting the bed)
Fix any issue found here
