I purchased a rather nice looking 0634 5019 and although in working condition it was acting ''funny'' i mean when pressing the chrono button the display goes blank for some time plus i could not set the time for the same reason(pulling the crown and pressing the buttons make the display blank for some time).
I opened the hatch and a wrong battery was fitted(if i remember corectly a 391 battery).
I tried with 2 diferent brand new 386 silver oxide bateries and the watch is dead,i mean no LCD no backlight, nothing.
Putting back the ''wrong'' battery and the watch ''works'' ofcourse with the issues mentioned above.
I checked the new batteries and no issues with the voltage,both good,the connections also looking pretty clean in my eyes(although not an expert).
Any ideas guys before having an expert to have it checked?