@alzhao i would be very careful in advising anyone to try this on a Mango MT300N-V2 thats 2 routers i have tried locally to upgrade from 3.203 using snapshot as advised and its broken both. Looked as though it was installing fine verified the install but upon reboot it fails to come back online instead just continues with a single flashing light repeating for power.

P.s the update worked fine on an AR750S just seems to be an issue on MT300N -V2

going to try the unbrick method to reset