OpenWRT is opensource operating system based on linux for your router, this operating system size only few megabytes. Your router exacly is small computer like your pc or smartphone, this operating system can install many application for adding more features, i used for adding usb function like samba / file server external harddisk storage and / or printer server. This operating system use network (from browser) graphical user interface, but if you everyday using windows pc or mac you need get to know more linux especially terminal / cmd / ssh remote access for better navigating all ability of linux, but graphical user interface is enough.
This is mirror latest or exactly the last firmware openwrt for tp-link tl-mr3040, this is because openwrt website moving directory of download address (in 2018) so you cant download directly from openwrt website. There no modification i do, its 100% original firmware i sure. I will give you direct download link from our server bellow (This site using US data center location but for download using Indonesia data center location may be slow for you).
MR3040 have many version but majority only 2 version, version 1.x and version 2.x, version 2.x have mode switch near lan / rj-45 port, minor version is compatible “theority” like version 1.0 compatible with 1.1, version 2.0 compatible with 2.1, but version 1.x not compatible with version 2.x and vice versa. I have been tested version 2.x at hardware 2.1 and work correctly.
You can do recovery by using serial port at mainboard, yes today you need usb to serial, little bit electronic skill, is maybe easy if you know more arduino. Disclaimer, no guarantee in you fail to attempt firmware but i will help, you can discuss at comment section.
Bonus tl mr 3020 open wrt mirror firmware
This is based in OpenWRT 17.01 November 2019 have security hole and will not maintenaned anymore. This is because openwrt nowadays need more flash storage and ram memory. Today ideally you have more than 8mb flash memory router and more than 64mb ram memory router. But if you thinking again, factory firmware is more outdated hahaha and more security hole. If someone need factory firmware just comment i will help provide the latest / last factory firmware for you.