The bike I bought 2nd hand had an old tail light which had a failed seal which meant it filled with rainwater rendering it useless, so I purchased another one, soon after I had to go shopping late one afternoon when I came out I went to turn the TL on it would not turn on, a couple nights later I went outside the light had come on of its own volition and would not turn off.
I went back to the bike shop they gave me another TL for free, weeks later after again going shopping in the late afternoon when came out and tried to turn it on it would not go on, like the other one it came on of its own volition nights later and like the other one it refused to turn off .. I went back to the same place and bought another tail light.
Days later I had leave in the dark to make an early morning appointment and gor blimey the new light would not turn on, even after I had tested it minutes before, I plugged it back into a USB port on the computer where after it started and fitted it back onto the bike while it was still flashing, when I arrived at my destination it would not turn off.
It took a girl in the doctors surgery about five minutes to turn it off .. back at the bike shop the dude at the counter took it from my hand and turned it on .. he told me everything was fine so I took it home, the same thing happened about four weeks later in the early morning it would not turn on at all, when I went back to the shop the same man turned it on with no effort then ordered me to get out of the shop.
Following his instructions, I got on my bike and went about one bike length before falling off and shattering my shoulder.