Casio GIEZ Ti-Rubber GS-300 Caliber 2301, ca. 2003
A view of the Caliber 2301 with the metal shield removed
Please note that the original watch unopened should have a sticker telling you that you will need to short the "AC CONNECTION AC" after a battery replacement. If you look very closely, you see some tiny marks on the gold contact from the circuit board below the right end of the "AC CONNECTION AC" arrow. That is where one end of your tweezers goes. The other end goes anywhere on top of the movement plate. And while shortening, make sure you do not touch the coil which is quite close.
The sticker was originally placed over the SR920W inscription and the SR920W battery. When I changed both batteries - SR621W for the analog part, SR920W for the digital circuit - for the third time, I noticed that the plastic sticker started to discolor and so I removed it.