I'm still rather confident that flashing via push-button tftp is likely to just work.
With tftp, the router accept of firmware but doesn't install it. I'm searching about a way to bypass the currunt firmware and install a new one.
Tried about 5 times now. Here's the steps i followed. Give me a 5 minutes please. I will post the exact method with screenstots.
In that case, as you're basically blind, serial console access will be the easiest way out.
Four screws on the bottom, a little prying to unhinge the clasps, 3.3V based (unpopulated) 4-pin serial connector pretty much in the middle of the board, between spi-nor and SOC.
Router pulled the file restarted. and nothing. Still in the same version it was on. To check if the method is correct, I selected the same version as the router's in, it get's sucessfully installed. I'm saying it was successfull bc it behaved the same when i tried using the gui.
Same version: Takes about 15 or 20 seconds. - Get installed
Any other version including overwrt: takes about 5 seconds - Not installed.
I'm confuced about this. Is there some kind of firmware lock to feep me from selecting any other version?
Found the port. How do i do it? Can you give me the way to it?
have you tried http://downloads.openwrt.org/barrier_breaker/14.07/ar71xx/generic/openwrt-ar71xx-generic-tl-wdr3500-v1-squashfs-factory.bin
?
You need a 3.3V(!) based USB-to-serial adapter. These sell for ~1.30-1.50 EUR/ USD delivered via the slow boat from abroad - or starting around a fiver from a domestic distributor (cp2102, ch340g tend to be fine. (typically) counterfeit ft232rl may cause grief on windows, but tend to be fine if you run linux).
Follow the pinout on the device page of your router, GND to GND, RX to TX, TX to RX. If you don't see any output, reverse rx/ tx - never connect Vcc/ 3.3V (unless you really know what you're doing and why).
First just have a look what the upgrade procedure (both GUI based and push-button tftp recovery) has to say about the OpenWrt factory image, that will give you hints why it rejects the factory image.
In order to flash OpenWrt, I'd interrupt the bootloader by typing the 'magic' tpl password at the right time (repeat it during earliest boot, until you end on the u-boot shell). Then tftpboot the initramfs image, use bootm to boot into it - and then use sysupgrade on the RAM-booted initramfs image.
There are more detailed descriptions about general serial console related things, as well as more specific advice for your device in the wiki. tl-wdr3500, tl-wdr3600 and tl-wdr4300 are very, very similar in terms of hardware, so most of the advice given there applies to all of them (apart from the actual firmware images/ names, of course), e.g. https://openwrt.org/toh/tp-link/tl-wdr4300_v1#de-brick_or_oem_installation_using_the_tftp_and_rs232_serial_method does apply.