Restore TP-Link C60 v3 (BR) to Stock Firmware [AC1350]

You may need a serial connection to the C60. Have you studied the old posts contained in this link?
https://openwrt.org/toh/tp-link/archer_c60_v2#debricking
links to:
https://forum.openwrt.org/t/help-in-unbricking-tp-link-archer-c60-v3/62642