LR2 Build with Rambo 1.4

I am building an LR2 and in the process of finishing up the electronics. But I am having a problem
I have loaded three different .hex file using Xloader from this website for the Rambo. When I connect to the board using UGS I get the same results. The load just seems to lock up.
See screenshots

If I type $$ and get the error GRBL is still booting. I’ve waited quite a while and still get the same message.
I have two Rambo boards one bench testing and one on the LR2 fully wired and both give the same results.
Can anyone help and tell how to fix this

AFAIK, you can use UGS with Marlin, and the firmware at MarlinBuilder releases is all Marlin. If you can use it, you at least have to tell it to use Marlin. $$ is only grbl.

You can use cncjs or repetier host.