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Good photo D3 is across the rail "BAD". Symptom blown 555. possible cause reversed at one stage blew D3 then blew 555. Still could be a zener for overvoltage protection fairly heafty diode (or Zener).
Check D3 (get the number) and replace anyway. replace 555 again if needed. Only one more component left to replace Q1. Fairly cheap items to replace, so would do them all.
Modifiaction - place inline fuse in lighter wire with god know current rating, need more testing for that.
Advice - I wouldn't buy one in the future, 2 design flaws already mentioned. (apologise for the bad)
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