How bout some pictures of the batteries? Where did you buy the Shockli’s? Did you have 18650 adapters in when you tried the GA’s? Are your batteries fully charged? If not the modes won’t work, other than low.

I have the ring removed and my light works fine. Ring on or off, the cap screws on the same distance. The end of the battery tube has to touch the retaining ring in the cap to complete a circuit. Otherwise, the light won’t turn on at all. Commonly referred to as “mechanical lockout”