To gain access to the terminal if u-boot is in bootloop, send
tpl <null terminate>
Enters into the shell.
@finsharp, welcome to the community!!!
Is this just information; or do you need assistance?
Just for information. I had this problem today where I couldn't figure out how to interrupt the uboot process.
Thanks for the warm welcome 
I used docklight to send the command as soon as the router rebooted.