[SOLVED] I need to hijack this very old thread, but i've been doing the same thing as the previous guy, but i have also tried updating with the .trx like you should, it refuses to update no matter what i do, trust me i've done everything and so far all i can think of is my router is just broken from factory :/ I'm currently stuck on 3.0.0.4.374_979-gbc8961e since i bought my router and i haven't been able to update it since purchase.
Edit: Had to put router in rescue-mode and do a firmware-restoration with the latest firmware, finally.