Hi Danial, if you have connectivity through the MGMT interface (when doing ping vr vr-mgmt a.b.c.d) you should be able to download the firmware from tftp server.
I'm wondering if the TFTP is up and running without any issue. To confirm that I would recommend you to open a wireshark in the TFTP server and try to download the firmware from the switch VR-mgmt. Then you will be able to see if the requests are being sent from the switch and receiving by the server.