Backlight fuses can blow on iPhone 6S even if battery is disconnected.
I replaced the screen in an iPhone 6S and the backlight fuse blew even though I disconnected the battery first and worked in an anti-static atmosphere. The glass on the original display was badly broken and the home button was flopping around in its place because a lot of the glass was gone around it. The customer wants to hold me responsible but honestly, I did nothing to incur the issue.