olight m21 only low light level works

just bought an m21 for my brother. Worked fine one time then only the low light level comes on. Switching levels does nothing but it does turn to strobe on the third switch. Then back to low. The strobe is also on low. Any thoughts??

Possibly low batteries?

Could be defectinve tailcap switch.

Sounds definetely like empty batteries.

Can't be possible though, nobody would post such a thread before having tried new cells, even if the first ones should have been new...

Check if the retaining ring in the tailcap sits tight, many M20 problems were caused by that ring. If neither new cells nor tightening the ring bring it back to normal life, contact the seller in order to send the light back!

NB : Use quality cells only, I already had new crappy cells working less than 10 minutes in a light until it dimmed down...

new batteries didn't help. On it's way back.