latest MM
https://canaan.io/downloads/software/avalon6/mm/2016-08-15/ dated 2016-08-15 get the file that says 2M.
rpi not sure if that's b or just the first rpi.
https://canaan.io/downloads/software/avalon6/openwrt/20160726/brcm2708/bcm2708/openwrt-brcm2708-bcm2708-rpi-ext4-sdcard.img
the one with 76M
rrpi 2 b
https://canaan.io/downloads/software/avalon6/openwrt/20160726/brcm2708/bcm2709/openwrt-brcm2708-bcm2709-rpi-2-ext4-sdcard.img
the one with 76M
rpi 3
https://canaan.io/downloads/software/avalon6/openwrt/20160726/brcm2708/bcm2710/openwrt-brcm2708-bcm2710-rpi-3-ext4-sdcard.img
the one with 76M
have you tired to run the ones in question one with one rpi ?. just them by there self ?. make sure the usb converters lites are flashing as well as in the back of the miner an are good and plugged in good . move the usb cable to see if the light changes color or flashes different.
what PSU are you using ?. an they did run good at one time ?. do you remember what may have happen when they started under hashing ?the fans do spin up @ start up ? if worse come to worse talk to lightfoot on the forums he may be able to repair them if they some how became DMG., hes seems like a good guy an is reason able price wise.
https://en.bitcoin.it/wiki/AvalonLook at this link there might be some thing there to help you and with what each error means that fanatic26 is talking about there is another link to put in the error code that will tell you what it might be. sorry i no longer have that link my miner hashes like it should after i hocked it up to a 2400 watt Server PSU .
you can ask canaan they may give you some help but unless you bought form them direct you may not get much help but they will help you if you bought from them direct. not sure though if they will any more for the A6 .I know they won't for there A4 .which i still have a working one i don't use not worth it any more unless BTC jump to 20 k a pop ... in fact they sent me a free inside controller one time for my A6 which i fucked up by mistake and ended up buying one off of sidehack on the forums who is also good at what he does.
other then that i have run out ideas with out having the miners in front of me which to be very honest i don't want unless there mine my repair days are over unless there mine .. i wish i could have fixed it over the forums but still ask for help if you need it, if i know I'll share it. some others might as well..