A customer slides a handset across the counter and the screen is stuck on the temperature warning \u2014 white text on black, no passcode entry, no home screen. The owner says it was fine until the screen replacement yesterday, or the battery swap last week, or the charging-port job two days ago. On the bench, the first question is not how to cool the phone down; it is whether the warning is a one-off environmental event or a comeback that will return the moment the device warms up under load. UK shops that treat every temperature alert as a simple cool-down job risk a second visit, a parts credit, and a reputation hit. This guide separates the environmental warning from the post-repair fault, gives a repeatable bench sequence, and shows where the labour time and parts risk sit for a trade operation.<\/p>\n