Okay the first part is
When the mouse is clicked it checks if the recharge is done. If so it that triggers the flash and subtract the recharge by 20 making it 0 again ( i would change it to set )
Line 2 is basicly every 0.25 secounds if the recharge is less then 20(not done) then it adds 1 to the recharge.
Line 3 is displaying the recharge.
Thanks to @Bburg800 for the capx example. Any question feel free to contact me.