5mW greenie Stops Working

First, I was using the 5mW green pointer with higher capacity batteries than the stock AAAs. I used AA and up to F batteries (long D). So, I was testing the pointer with the F batteries for about 10 seconds (they Did Not die during operation while output was similar to normal), and when I hooked the front of the laser back to its original AAAs & casing, I discovered the laser was not outputting any further. At first thought, I thought the F batteries burned out the diode or something within, but while I was trying to figure out what went wrong, the laser ignited normally for about 5 clicks and it went dead again.

Could something not be in place?
Obviously the diode is Not Dead and the circuit board was not significantly damaged, otherwise it would not have turned on for the last time. Perhaps something shorted?

Any thoughts on what I should do? :/
(this is a DX style 5mW laser pointer which has worked very well for the time since I had it)

Check your Battery contacts or maybe you Switch has
become intermittent... or you have a Cold Joint on your
driver...

Jerry

I am the first time to hear such cases too
Will come to see answers later .