I bricked my MR3040 last evening also. Unfortunately, I have already written to tp-link tech support telling them that I had tried installing a custom firmware and they advised me to press the reset button, which I had done without any results and she said that beyond that, they may not be able to assist further.
I'm trying to figure out how to flash the latest stock firmware back onto the device using the U-Boot technique. When I turn the router on, all I see is the power LED on and nothing more. There is no signal on the Ethernet port. How do I connect the modem to my laptop which does not have a serial port? Do I connect the modem's power/micro USB port to a USB port on my laptop (no device gets detected when I do that) or do I use the USB port on the modem and a USB port on my laptop? I have two USB-male Serial RS-232 cables and a female-female converter that can allow me to have a USB to Serial to USB cable (using this technique didn't show anything on putty either ). Somebody please help...