Rear Drum Brake Issue

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Just about 24 hours ago, my car randomly started slowing down while I was going on the highway (~75mph). When I moved to pull over and slowed down, all of the sudden I felt my rear wheels lock up and I sort of skidded to a halt from about 15mph. I got it towed home hoping it wasn't the calipers seizing up on me. When I got around to looking at the rear braking systems today, I discovered that my rear left side drum brake shoes were awkwardly worn like they shifted outside the drum portion of the rotor a bit and the edge of the drum wore them down. I also noticed the dust shield was missing entirely. I think since the dust shield sort of keeps the brake shoes inside the drum, and with my lack thereof, the brake shoes managed to weasel their way out and get caught on the edge of the inner portion of the drum.

My issue is getting those EXTREMELY low-profile hex bolts off so I can put a new dust shield on, ideally without having to remove the entire wheel hub to do so. I know I'll have to cut the old dust shield to get it off, and cut the new one to put it on.

I found the following link of instructions on how to change the dust shield, which sort of addresses the low-profile hex bolts. All the guy says is that it's hard to remove them and that using an open-ended wrench is the way to go. Well I tried that and the damn thing just slips right off. I feel like just using 2 more small 5mm hex bolts would have sufficed, but BMW agreed to make life difficult for us DIY'ers. I'm tempted to rent a dremel tool or whatever it's called to cut a notch in the head of the bolt so I can just use a flathead screwdriver. Is there any easy way to remove those bolts? Will hitting it with a blow torch help?

https://www.pelicanparts.com/BMW/tec...eplacement.htm

What about a temporary fix? If I fully retract that specific adjuster, and then possibly never use my E-brake (at least not while moving), would that temporarily fix my issue? I realize that wouldn't be advisable, but I need my car drivable over the next few days for work, and ordering a dust shield online will still take at least 5-7 business days for it to arrive. No autoparts stores near me have dust shields for my car. I'll be checking around some junkyards to see if they can save my skin by coming up with one, but I'm not going to get my hopes up.

Any advice would be great.

EDIT
Forgot to mention what car I have - 2002 325xi

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UPDATE

It wasn't the rear brake shoes on either side causing the rear wheels to lock up. I'm no longer sure what could be causing this, but I did record a video to capture the sound it makes. Below is the link (I promise it isn't me trying to advertise a youtube channel; I don't even have one). If anyone could take a listen (you may need to turn your volume up; I've never uploaded a video off my phone before), and give their two cents, that'd be great!