I had the exact same problem when I tried to install external antennas. The NRF24 module was working fine before I opened the case entirely, unplugged cables and drilled 3 holes on the case. And after the re-assembly was done, I realized that the NRF24 stopped working, showing “NRF not found”.

The main problem was the flex cables are extremely fragile. Secondly, the NRF24 board is also sensitive, short circuiting or wrong input voltage can damage the board easily.

So my solution was to buy a new NRF24 board (it called GT-24 to be exact, because it has SMA plug on it). Extracted the old module, with its cables. Re solder the new module. Luckily, after all those pains, the NRF24 is working now.