OK, since we are not able to see the screen, we will have to do step by step process.
First get in to Marvell>> prompt. now do
MArvell>> usb start
Marvell>> usb storage
the result should stated it have at lease one storage found. if not than you need to check if you have the uSD insert correctly and re do the step above to prove it. once you have it working then do
Marvell>> fatls usb 0 /
The result should show at lease have a file name "uImage
", if not than you have not successful load uImage
to the first partition as you stated in the first post, please go back and try to correct it.
If you do get correct result then please post your u-boot env so we can debug from there.
If it is possible please post each step result as is. it will help to understand the situation.