This light has an electronic lockout. Breaking the contact with the cell doesn’t undue the lockout. If you don’t know what the lockout sequence is, I guess u have to go the manual if u have one. With the head of the light separated from the body I pushed the sequence for undoing the lockout, (the switch is on the head) then screwed it back together and it works! Not sure I’ve come across this before on other lights. Yes, I had to read my manual to find the lockout sequence 
I have the stainless steel version running it on a 10440. It’s a nice looker!