I had no luck with routers GL-MT300A.
I bought 3 of them in 2016 year.
In the first router, soon stopped working Wi-Fi.
The second router after pressing the reset button for 10 seconds stopped working at all .
How can I bring them back to life?
PS. Third router with Firmware 2.265 is until still working.
You tried de brick using uboot?
alzhao
No, haven’t tried it yet. Thanks for reminding me!
Hooray! 
MT300A has already been restored using your method!
alzhao, thank you very much!
To great unfortunately, the other two routers GL-MT300A cannot be revived with the same method.
The firmware is loaded, the update process reaches 100%.
But more nothing happens, the update window does not closed.
In the beginning, I used the openwrt-gl-mt300a-clean-2.264.bin firmware, which previously worked fine on all three GL-MT300A.
Then I tried to use the new firmware gl-mt300a-3.0-1011_clean.bin. But this also did not give good results.
But after trying to revive routers are still unavailable at address 192.168.8.1 (also 192.168.1.1).
As a result, out of three routers, only one works.
And what do I need to do now?
You need a USB UART adapter, open the case and connect to the router, check what is the output.
Ok, I seem to have an adapter like this.
How to use it? Is there an instruction for MT300A recovery for it?
And the second question is, why did these two MT300As work fine at first and then stop even though I didn’t reconfigure them?
I have no idea of why these two does not work.
If you connect UART adatper, you can see the output from UART, thus knowing what is happening exactly.