I'm familiar with this pop door from Amazon. I have read posts about it,,, and the negative points were;; Battery will not last as long as stated. Second point is,,, motor is not very strong,,,,, although it will work under good conditions. I'm in northern weather snow/ice country during...
All the mechanical are enclosed in this portion,,,, including the battery. The two screws I circled in RED are how to get to battery and everything else.
Closed position
I use an Adoor1. I do not have sand in my coop, but there is sand/ dirt nearby in the run. The channels on my unit are not that tight fit, so debris does not jam the channels.
My unit has been working fine since 2017.
Ador1 is considerably higher priced than the Amazon unit you posted...