User hostile design
|The forbidden hole
"Removing the sim tray will trigger the tamper detection system in this device".
That would have been grand, SumUp. None of the booklets in the packaging seem to mention this. Some people might even think this is a "factory reset" hole. And press it because their device is malfunctioning or they want to sell it to someone else.
Other people on the internet have reported that not charging the device for an extended period of time (like: 6 months?) may trigger one of the tamper detection mechanisms, as well as shocks (due to accidentally dropping the device for example). In all of these cases you're SOL. SumUp has no interest in refurbishing/repurposing these devices and they will not give you a discount for sending it back.
Repurposing the hardware is pretty difficult since most of the parts that can be easily disassembled have no data sheets or mentions at all on the internet.
Disassembly and teardown
Modem and battery
|The Quectel modem with
some redacted unique numbers.
Motherboard back side
On the left we can see a battery (cell with the yellow insulation) that is presumably used to keep the CPU awake so it can trigger the tamper detection if the Lithium Ion battery is fully depleted.
Main CPU (+ bootloader diagnostics)
Card reader tamper shield
|Part number on the flex cable that carries display
|Other side of the display signal flex cable: