LEDE may not be stable for you 4/32 device.
Might be better to stock with OEM firmware or Openwrt 15.05.x (that has smaller older kernel).
So, I think that you are going to waste effort in trying to unlock the device.
(If you search the forum for 18005, it reveals that using bootloader TFTP flashing might the best option to overcoming locking. But I am not familiar with TP-link locking, so this is just based on 30 seconds casual search)