How many times have I been crawling on a mucky floor plugging SEB's back in?!
We ty-wrap strap the box lids on in some aircraft these days.
I suppose, strictly speaking, this constitutes maintenance without a CRS (can't maintain in the air). However, it is safer to have the system restored to serviceability ASAP to prevent potential damage/disaster (and keep the customer happy!).
While I worked for a major ME carrier in the 90s - one of the first to install seatback video in all classes - cabin crew had (have?) authority to replace screens, using a "scissor" type or insertion tool, depending on the screen. Invariably, they fitted them all wrong, in many case not even connecting the screen.