Resolder all the USB connector pins (red box'es), on all 3 USB connectors to be sure they are functional. (on this image the top one is defective)

The reason solder points break is the connector support is soldered onto the board on one side only. Not by the arrow. Thereby adding stress directly to the soldered pins.

In addition the connector pin (square) near the U2 marking is too short and therefore may not be soldered properly.

see 2nd image for example of front support pin is pulled out of solder area.

Note that the board on the newer 'Smahagel' model of this charger, which has a 100-240V voltage rating but otherwise looks identical externally, looks slightly different and has both supports soldered to the PCB. The fix still applies though.