Finally, It’s Done as I’m writing this post, Just as I suspected it’s attached via the internal USB header which is allocated for firmware flashing, I’m thanking @vivek from the Service team for doing it in less than 25 mins. Here are some pics
Opening the Top rear cover and reflashing the software to disable the internal sim.
The Microusb port
the Old antenna removed and taken back 
The finished product, The big black box is shown here in the top right is the 4G module crappy workmanship the seal does look like an after requirement which they forgot to tell while ordering, No external antenna for this though also no cap provided for the SMA connector, definitely, it’s gonna oxidize
My property in Ather’s Hand 
, The person took it back saying the office requires it back 
, Is it not my property? he said they will disable it and give it back to me, Fingers crossed, I did tell him there is nothing to disable it and it’s just an antenna
The whole experience was seamless, not to mention after loading it took 3 restarts to get the signal, but once it got it, the maps were loading faster and app connectivity is locating the scooter much faster