This is my experience using the CTX with Modded O Rings on the USB and battery compartment to Frogmaster's YouTube video specs. The USB port eventually leaked and
I got a "USB Connected" message on the screen which ended my hunt and bummed me out. I was bummed because I had other issues with the CTX like streaks on the display-now another problem. When I got home, I left the USB cap off and let it dry out for about a week. After about a week, the detector worked again. (Looks like the USB port is sealed off from the rest of the unit). From that point I no longer use a o-ring on the USB, I put a heavy amount of silicone (di electric) grease on the inside of the cap and some on the threads. The grease ends up sealing up the whole entire USB contacts. So far no harm done.
For the battery port, I've upgraded to the thicker o-ring. I've also have 20 back up o-rings because to clean the o-ring, I use a micro-flat tip screw driver to dig it out of the recessed channel which causes minor damage to the o-ring. (It's in there tight). After charging my battery, cleaning the o-ring and chamber, I apply a bead of silicone grease into the chamber, on the o-ring and on the contacts of the battery and detector unit. I put back the battery and place a #84 rubber band on the snaps. I found these rubber bands in the Hilo Hawaii Home Depot, next to the gun safes.
I have done beach hunting here where I've been picked up by a 6 foot wave, slammed into the sand and come out with no leakage and detector still working.
Just sharing my experience and hope it helps you water hunters.
Jay