I have the same device, bricked it for almost the same reason, the section where you should use a .bin image from OEM based on whether it has 'boot' or not is wrong, I didn't have the 'boot' in the image and therefore should've no problem flashing the original firmware back, I had the same problem with sysupgrade, it didn't work, so I used the mtd method, which bricked the device since it loops the same sequence with the LED's flashing, I also tried TFTP methods based on hardware similarities with older routers and failed.. I then bought a USB TTL device and used telephone wires for the connection.. a multimeter was used to check UART TX,RX,GND,VCC, and I'm not so sure it's the same as in the picture, from left to right, the first two have voltage of about 2.7 each the others don't, using a continuity test the 3rd was the only one to beep with other components in the circuit board and I deemed it to be GND, so if I checked it right the image holds up, yet after connecting GND, TX, RX and flipping both TX and RX, fired up 'screen /dev/ttyUSB0 and started to wait for something to show up (shorting the wires intentionally proved the TTY was working since it printed some characters), connected the device to its power adapter and nothing... after a few tries I thought maybe its something with the ground, shifting the ground cable caused a blackout... I have NO IDEA as to why there's no response... but it's very similar to this.
a few notes about the pictures:
- I used analog voltage, I later switched to DC and got 2.7V.
- Telephone wires are securing the device to the USB TTL
PREP work (Multimeter etc..):
So I'm stuck and I'm right there with you @tplinkuser2