Hello runerd! You seem to have done pretty much everything to get Firefox working! That's dedication right there! I have looked at all four of the crash reports you kindly provided, and all of them have the same core crash reason. And all of them seem to be common problems with AGM phones as you can see here. I as a volunteer can't fix this. This bug is reported in Bugzilla. Hope I could provide some information, and if I did, please mark this post as solved!

Hi Vendell and thank you for your answer and the link to that Bugzilla report! I followed the Simple Android build instructions and have managed to run my own build of 60.0a1. It crashes the same way. Don't know if I'm a little over optimistic here, but I was hoping to figure out the cause and just remove it from the code and rebuild :) But it's my first time here at Mozilla. Do they provide help in those Bugzilla reports?

Haha, did a small change in GeckoApp.java and now my nightly build doesn't crash anymore :)

Same problem here! Also agm X2 and crashing Firefox... I've been using Firefox for years now, so very inconvienient

It's nothing wrong with the phone. This is a confirmed Firefox bug which is triggered if the directory /res/fonts/ exists in the file system, as it does on the AGM X2. See discussion here: https://bugzilla.mozilla.org/show_bug.cgi?id=1373964

Does this still work and how to do this?

The bug must be fixed by the Firefox developers. Then I guess this will find its way into Firefox Nightly, then Beta, and finally the official release version. In the meantime your only option is probably to build your own version of Firefox (Fennec). In the bugzilla thread there's a pastebin-link with a quickly made build-howto. Your completely on your own, but if you're desperate enough like I was you'll figure it out :)