Mode sequences should be High - Med - Low - Disco - SOS, but when I checked, it’s Dim - Dim - Dim - Disco - SOS. I know it’s broken but I’m not smart enough to find the problem in the driver. I can only think about driver swapping.
I’ve checked the LED, replace it with other LEDs but the problem persists.
Driver diameter
Driver top
Switchboard top
Switchboard bottom
I’ve contacted the manufacturer/company, asking about the problem but they can only advise to send back the flashlight to their technician which is not available in my country.
this look to me like some sort of buck or buck boost board (round), because the light take in one 18650 or two CR123. The rectangle board is for switch and Attiny microcontroller. It seem like maybe part of the connection to the switching driver (round) may be bad. If the SOS and disco mode work, the microcontroller seem to be working. Unfortunately difficult to debug without oscilloscope.
It sound to me that you can easily replace with an online driver of 22-23mm. If you just use single 18650, there are many driver available with lot of modes and BLF firmware since your LED is only a single XM L2 LED.