Yes so you got 2 faliure, one when restoring tplink fw, and one trying from uboot the second time.. Also probably wrong parameters in uboot (printenv would have been useful to inspect that) makes me think your flash chip was failing.... Time to upgrade to 16M xD
For you nebbia88 and all others who can learn something from this:
I could not get to rest about my router not wanting to cooperate, so I followed the nice tip from nebbia88 to remove the flash chip from the bricked router, and piggybacking it onto the flash in the working router. I lifted pin1 of the "good" router, and attaced some wires and a micro alligator clip so I could select the flash manually. I did this fully aware that I might nuke the only remaining hw. This took some hours, I wish i were 16 again :-)
I booted the router with the good flash selected, (115kbaud/7S1). I attempted to copy boot+firmware, but leaving the two highest 64 k blocks intact,
so I used a size of 0x3dffff, not touching sector 3e (config??) and 3f ( art??). I switched chip select, erased 0-3dffff, and was greeted with "62 sectors erased", which seems correct. I copied ram to flash. Without changing anything, I switched power off / on. SAME BEHAVIOUR AS BEFORE, leds 1 x x 4 5 6 7 x x ON, nothing on the terminal.
I repeated the experiment, but still in wasp> but this time I copied only the boot, i.e. the first 0x20000 bytes.
Power up, SAME AS BEFORE.
New repeat, this time all first 62 sectors, and boot + firmware. Tried bootm 0x9f020000
## Booting image at 9f020000 ...
Uncompressing Kernel Image ... Too big uncompressed streamLZMA ERROR 1 - must RESET board to recover
and a dead router, no uboot, ledon 1 x x 4 5 6 7 x x
(note the pattern, it is NOT power + switch ports, maybe it means "xxx -data corrupted, cannot start" ??
Last try before throwing the piggyback flash in the recycling, I restarted again, but this time i copied ALL flash, 0x400000. Power off/on, and now the thing is booting. So, this is now an identical twin, and MAC addr etc is screwed., but Uboot works. So, 2 possibilities:
1. there is something that needs to be in config or art, and that something prevents uboot to run. Partition chksum??
2. there is a bug in uboot, so the copy operations do not do what you ask it
So, now I am going to transfer the chip back into the "bricked router" but I think I'll save that for tomorrow :-)