Problems installing on MikroTik 760iGS


I'm testing the MikroTik hardware to see if it will work fine in a setup I have. I'm trying to install OpenWRT following the directions here

Using the initramfs image here

and I don't seem to be able to get the initial OpenWRT install to boot up on the device. I have it plugged into another OpenWRT device and have that one set up using dnsmasq to serve up the image file. I can get the 760iGS into netboot mode and see it request and get served the image file from dnsmasq. It chews on this a bit, beeps once and then twice, and then it's back like it was before without OpenWRT on there

Can anyone help me?

Got serial console access?

Not at the moment. Was trying to find out how to solder / attach the port on the motherboard but haven't found much info on that yet.

Haven't cracked the box open yet though so maybe it's obvious