Pine A64 does only boot with Android 5.1

[tophneal]

first, i'd say dont count on Remix OS to boot. I could never get it to, even when it was under active development. You might want to try using that slower USB2 port. sometimes it helps for an IMG to be written more slowly.

You might also try using Rufus to write your SD (I hear it's a popular Windows alternative to Etcher, but I've never used it)