I’m only aware of that pin pads cannot be hacked remotely, so it must have been an inside job. Somebody wearing a uniform, claiming that he’s there to do upgrades or maintenance.
The PCs the pin pads are connected to can be hacked, which amounts to the same thing.
Generally the thieves attach a device between the pin pad and the PC to capture the data. The stores are required to secure the cabling to prevent this but most do not.