I learned that lesson as a 12 year old in the early 90’s on an original IBM PC 5150 with a 5151 monochrome monitor, fucking with TSR’s in DOS 3.1. It must’ve made the graphics card change timing modes and the monitor immediately blew a fuse. My dad then soldered in a fuseholder so the fuse in the monitor can be replaces as needed.
Out of fear of doing further damage, I did stay away from the particular TSRs that had any relation to changing video timing modes and it didn’t happen again.