Whew, that's good to know, thanks. I should be able to solder it if you could give me some directions on how to do it. And between the 4 contacts, which ones do I short circuit, a single left and right one or lower and higher?
You can make short circuit between either nearer pair to turn controller into flash mode, this is what the button does.
I would solder like below.
1. apply flux on pads and remove solder with wick.
2. clean and wipe pcb with IPA if available.
3. apply flux on pads again
4. apply little bit of flux on contacts of button switch with care.
5. clean iron tip and put solder on it
6. put the switch on proper position with tweezer
7. solder just one of contacts. retry if its placement is not good.
8. solder other three contacts. don't solder them until the switch is placed at right position.
Hope this helps.