And yes, I am using a wireless connection between my laptop and the router.
That is probably the reason for the fact that you loose response of at Marvell prompt.
I notice a T when it uploaded the kernel. That means it had a timeout
Probably similar problems happens when installing the firmware using the installer. The wireless is not so reliable.
I suggest you repeat it using a wired connection.
If you use the installer again first delete the partition table
About your question, manully setting up network settings, that needs adaptation of the nas database, cannot be done from u-boot console
But with the standalone kernel we could manage that. But that will not be tonight, I go to bed, sorry
But tomorrow I will have some time