It’s not difficult, remove two small phillips screws in base, the base piece will snap out. The back piece is a bit more difficult but snaps out. I used small screw driver to release the snaps on each side . The internal antenna connect to the circuit board with standard micro snap fitting. I used an antenna
https://www.amazon.com/dp/B06WD7FZV4/ref=cm_sw_r_cp_api_i_mqx6CbRN9DP83
It has connector that snaps on board. Fashion a hole to fit the sma fitting on other end of pig tale. Stuff the lead in the cube and reassemble.
Photos:iCloud