Ouch man, I hate it when that happens... but I think I may see the problem. All of those new solder joints you made look like they aren't "tented" over the lead and onto the pad, rather just a blob on top of the pin that may or may not touch the board. I'd go and suck up a lot of that solder (you shouldn't need that much anyways) and make sure to heat the pad and lead together to help the solder flow down onto the pad. Considering it is the only thing you have technically done to it that would affect how it works, I'd start there. Then I'd start replacing things that talk directly with the cartridge, you may have damaged one with heat from soldering.
