From AirOS 5.5.X to 5.6.X the size of memories on the flash changes so that flashing OpenWRT (or other non AirOS firmwares) bricks the device. From https://wiki.openwrt.org/toh/ubiquiti/airmaxm "Special Firmware Note: AirOS XM.v5.5.X images used U-Boot 1.1.4.2-s594 (Dec 5 2012 - 15:23:07). The OpenWRT image can be successfully flashed onto these versions of firmware. However, in July 2015 Ubiquiti released a new version of firmware XM.v5.6.X. With this firmware a new U-Boot version was released, U-Boot 1.1.4.2-s956 (Jun 10 2015 - 10:54:50). The newer U-Boot version changes the memory size and starting address for rootfs, cfg, and EEPROM. LOADING AN OPENWRT IMAGE ON A U-Boot 1.1.4.2-s956 WILL CAUSE THE DEVICE TO BE BRICKED!!! If the device has XM.v5.6.X, an older version of XM firmware can be loaded from the AirOS webgui (for example XM.v5.5.10) and U-Boot will be overwritten with the older version. OpenWRT can then be loaded onto the device successfully." Anyway if you have a way for un-bricking such devices let me know, as I have 4 devices bricked this way. There's also a bug report on this problem https://dev.openwrt.org/ticket/20982 Bye, Ilario PS sorry for cross-posting -- Ilario Gelmetti iochesonome(a)gmail.com igelmetti(a)iciq.es ilario.gelmetti(a)estudiants.urv.cat