Locked bootloader? Ugh. Hate when they do that. My last phone was a Sony phone. It was unlocked, but pretty much every other variant wasn't so the development was weak compared to other similar quality phones. But yea, unfortunately, stuff just goes bad. :/ I hope there's another solution, but not sure I would hold my breath as it's such a unique problem. I read the forums ALL the time as well as experimenting heavily with my phone and fixing, rooting, etc other people's stuff and haven't seen anything I can think of that would cause this. Not saying there isn't an answer, but if there is, I would imagine it's rather obscure.
Just for the heck of it, searched for: GPS apps crash system - and found other phones that have suffered from this, such as Blackberries:
Just thought of another thing, maybe you can plug it into the computer and get a logcat running, then make the phone crash and the logcat should catch what fails before it crashes. Now the logcats are confusing to read if you aren't used to them (I'm learning slowly). You could also try to run it from the phone if you don't want to use the computer with something like https://play.google.com/store/apps/d...rg.jtb.alogrec as it saves it continuously to the phone's storage.
Hm I attached the screenshot of the logcat while the systemui force closes when using the notification toggle for gps. I really can't read any of that though
Well I'll keep on trying, but I don't really know what else i could try anymore.
But thank you for all the help!