Could be the BCM or a switch. I would start by unplugging each door lock switch, one at a time, while the problem is happening. If that doesn't do anything, then I'd look at the BCM. Could also remove fuse # 15 under the hood and re-insert; might do something but I doubt it.
No reset that I am aware of. The fuse is #12 under the hood.
I had to access the back of fuel door, so here is how to get that far. I didn't remove the panel, but had enough room to get in behind. Might be enough for you. And there is a link to a Youtube video showing the whole process; Fuel...
On mine, the upper ballmount tore out.
OP's strut must have seized and broke off on the bottom. Pull the interior panel and report back.
On the struts, when I replaced them a year later, I got them from Mazda.
Thanks. Nothing on the fishing part. I couldn't get the a-pillar panel off, so was forced to fish it with an old clothes hanger.
The basics on the install:
http://chrisb.users.superford.org/Mazda_CX-9/Projects/Stereo/Stereo_Upgrade.html
Random pics and info during the install...
The mic's are all in the same spot. I pulled the dome light out then fished the wire in behind the roof liner and down the a-pillar.
http://chrisb.users.superford.org/Mazda_CX-9/Projects/Stereo/Stereo.html#2022-08-20
Measure your vehicle and get the appropriate ballmount for the height and weight. You want the trailer level. If not, you will have too much or too little tongue weight, which effects drivability. You can change the tongue weight by the location of the junk in/on the trailer.
Happy towing!