Nope, RAM size has nothing to do with it. Do you have an A-to-A cable and UART ?
For starters, if you have an A-to-A cable could you follow the instructions here and later pastebin what rkflashtool n gives you with eMMC mounted on the board?
For starters, if you have an A-to-A cable could you follow the instructions here and later pastebin what rkflashtool n gives you with eMMC mounted on the board?