It’s often start-up from extreme cold that is the problem…but if system can limp into power up - even if out of spec/not fully functioning, & then get a reboot/warm start self heating will often have taken care of things…xtals and oscillators can be a problem. I’ve seen telecoms systems in cold climes set to do that automatically (after 30 mins IIRC when they have been off for >few hours) as a matter of course…