I have a wonky DIR615-G2 that came standard with my UniFi subscription. It would randomly reboot and even fail to boot from time to time. Even trying to re-flash the firmware using the Emergency mode is iffy.
So, I figured out a way to at least get it to boot OpenWRT in a clean way. Essentially, I had to flash it with a DD-WRT image because the stock OpenWRT image does not work. Then, the standard method is to upgrade it to OpenWRT. However, that fails too.
So, I had to work out my own way, which does not require SSH running.
Essentially:
- Boot the router into emergency mode.
- Flash it with the stock DD-WRT firmware.
- Reboot the device.
- Telnet to the router.
telnet 192.168.1.1 - Transfer the OpenWRT upgrade image using netcat
nc -l -p 1234 > /tmp/dir620.bin - Erase the nvram
erase nvram - Erase the flash
mtd erase linux - Flash the upgrade
mtd -r write /tmp/dir620.bin linux - Reboot the device.
Technical Intercourse 