Looked into other router and also configured dhcp server on my linux machine. The MR3020 did not want to connect to anything. Even nmap could not find it.

Alas, as the serial console worked, the problem was obvious. It was configured to use a static ip, but no ip was provided. Hence, I totally bricked it.
Ouch, so dangerous. So lucky you can un bricked the TL-MR3020

Guys, with gusto88 experience, please be careful while applying setting
