Replace a fluorescent closet light with a new LED fixture

Our closets had 20" fluorescent tube lights that were flickering, and instead of buying more bulbs, I decided to replace the fixtures with new LED lights. This is made more complicated since the new lights require an external electrical box for the wiring connections.
Links for the products used:
LED light fixtures: smile.amazon.c...
Electrical box: smile.amazon.c...
Spackle: smile.amazon.c...

[@almanac520]

Thanks Preston, for the demo.
I just replaced my closets’ lights with LED.