Answered Ive got a major z axis problem

OK, so the Z home is not being attempted. This could be because the switch is being read as HOME all the time.
When the switch is closed it is home, open should not be. If you have a GCode terminal (from a host program like MatterControl) attached go to the terminal and enter a

G28;

and watch what it does (should be the same as you selecting HOME from the LCD) and then enter this and copy/paste the results back here:

M119;

That should result in something like the following:

Reporting endstop status
x_min: open
y_min: open
z_min: TRIGGERED

except for any Axis that is HOME you should see triggered. I suspect you have at least one axis reporting HOME when it is not and that is a problem with the switch or wiring or the RAMPS board. We can trace that back once we know.

 

PS the grinding on the X home is likely also switch related, but it can also be something getting in the way of the carriage movement -- let's fix the Z first

 

OK, the video shows that after the G28 the X is homed, the Z is homed* and the Y is not (because for some reason it went to center of bed rather than home).

I would start by reloading the beta firmware. The G28 should home in the front left corner, not the center of the bed.
The beta firmware is over here: https://help.robo3d.com/hc/en-us/articles/115000723672-Robo-R1-original-firmware
Look at the link labeled "R1 Beta ( No Autolevel )".

Then go to the link that describes how to load the firmware : https://help.robo3d.com/hc/en-us/articles/115000717071-Updating-firmware-with-Arduino

or read the section of the FAQ that covers it: http://community.robo3d.com/index.php?threads/faq-r1-r1-series-printers.19735/#post-119335

and then reload the firmware and try this again with the G28 and M119



*but it is not really home since it is not going down. That is probably an issue with the firmware or the switch (or the wires). We can sort that next. Home is the extruder parked on/near the bed in that front-left corner.

 

It is important to use the correct firmware because some models of the R1 have the switches wired normally open and other models have them wired normally closed. If you load the wrong firmware you will not be able to get very far

 

This works if all you need is a global Z offset. It will generically (across the entire bed) apply the offset to the Z.
Most people using autoleveling are better off with the M565 approach since it gets calculated into the leveling offset by the firmware.