Startup Woes

[z4v4l]

But regardless of the OS should there not be some sort of output to the display, even if it's an error?

Glad you got it working with Ghost's help. Just to clarify this point, ARM based boards like the pine64 are very dumb. There is no BIOS or EFI like on a Intel-x86/AMD64/PowerPC platform. Hence, if there is no OS on the microSD card, onboard NAND or other compatiable storage, it is as intelligent as a block of wood. First thing the ARM processor does is start loading data from the storage device, and it is at that point it starts realising what it is (via the power that is uBoot - which is essentially the ARM version of a BIOS - which is loaded form the storage device). 

So in a nutshell, no (or a blank or corrupt) microSD card on a pine64... you have a paperweight

Again... welcome to the party!

arm boards aren't any dumber than other platforms. all architectures start with the predefined address, pointing somewhere in the permanent code storage (Rom), be it arm or x86. arm cpu's on these SoC's start with Rom code, located in the SoC. then that romcode loads firmware from some non-volatile storage into SRAM and transfers control to it. and it's uboot which is nowadays arm boards "BIOS".
the only considerable difference, on the arm SBC's there is no such a thing like dedicated NOR flash storage for firmware. that's why fw is placed somewhere beyond MBR on the eMMC, SD. And then "shadowed" into SRAM by the romcode. In NOR, it could execute in place (XIP). But this is not architecturally forbidden, it's just
cutting off prices. Arm SoC's support NOR flashes, SPI etc, their romcodes might deal with XIP. some arm soc's romcodes can even load its payload through network, understand FAT etc.

For the topicstarter: to see output of your firmware, thus uboot, you need to attach your board to the terminal (your PC would be that), through the serial port (with the help of USB-TTL adapter).