[LEDE-DEV] Archer c7 corrupted firmware bootloop - tftp aborting - serial not working

[QWeRKUS qwErkus]

Hello,

Something went wrong with my last flash of an archer c7 v2, and now
the device refuses to boot. I'm trying to unbrick it without success
since.

1. TFTP seems to work, and I can send a recovery bin. I used a
stripped firmware from here
http://www.friedzombie.com/tplink-stripped-firmware/ - which used to
work great.
Unfortunately the router drops the connection after 30seconds without
installing the new firmware. The openwrt wiki mentions the possibility
of a header incompatibility when the flashing is corrupted, causing
the TFTP recovery service to reject the new firmware. The whole thing
is rather cryptic to me, and any help would be greatly appreciated.

2. I tried to get a serial access to the device, unfortunately all I
get is gibberish. Tried 115200 and 9600 baudrates, 8 bit, no parity, 1
stop bit, no flow control with either CP2102 or PL2303 usb uart
dongles.
Also, I can't boot the device with the ground wire from either uart
plugged in. Lights turns on, and just freeze.

Wasted tons of hours on this, and would really be thankful for any
advice/pointers.

best regards,

Felix