I purchased an A5-V11 (with battery) from ebay. It is the same exact "with battery" hardware as seen on OpenWRT's teardown pics. However, it is missing mtd_write.
I need to find a way around this.
OK-- Looks like there is a static compiled mtd_write (MIPS24k, same instruction set as this Ralink SoC) for the zsun flashing script that I had downloaded a long time ago. I will see if it can execute.
Nope. It refused to execute. So, I did the a5-v11-squashfs-factory.bin method. Pushed reinx as "payload.bin", and now it boots my switch just fine. Will have to see about getting it to do the needful in terms of network services and pals later, but for now-- Very happy with my new payload injector.