Why do you think that? A “dead modem” could absolutely cause a power management problem and result in a full shutdown or crash. The fact that they don’t have this issue with a different cellular modem seems to point to that. There have been examples of modem pieces breaking and causing possible shorting Librem 5 loses its modem - #10 by Dlonk . I should point out that not all “shorting” is the same and that it could result in dysfunction (modem doesn’t turn on) or destruction (magic smoke) — the phone having an immediate shutdown based on powering a specific modem would be one where I would worry about damaging the phone’s power circuits and, personally, I wouldn’t encourage playing around with that modem other than maybe investigating whether it was seated correctly.