[Verizon Samsung Galaxy S III] DuoDSG:
I am writing a thorough step-by-step of what I did since something I did along the way may be important for someone helping out to know. Sorry for the length, but I prefer to be thorough instead of wasting people's time with a lot of back-and-forth questions from not being clear in the initial post.

Current ROM:

Team Octos OCT-L-WEEKLY-20151219-0359-d2vzw

(Dec 19th 2015)

Current OpenGApps:

open_gapps-arm-5.1-stock-20151219

Current Modem:

d2vzw_VRBMF1_firmware

FYI, I keep the builds for any ROMs or packages I install-as well as the one I had previous to the one I am currently running- on my phone's external SD card so I can keep them organized and have them on-hand to revert back in case of problems.

The situation

1. After numerous crashes and freezes recently, I thought to get the newest stable release of my current ROM to hopefully remove these issues. The latest stable build is from 25 March. Using my phone, I went onto their homepage and downloaded the latest build. Or so I thought.

2. I rebooted into TWRP to install the new ZIP, wipe cache and dalvik, fix permissions, and reboot to system. During the reboot, the animation was different. I've seen builds change animations without it being a new Android version, so I didn't think much of it.

3. After it finished booting to the home screen, my phone buzzed every 2-3 seconds because Google Play Services kept crashing continually. It was 1am at this point and I had seen very similar Google Play Services issues many times before so I knew it would be a time-consuming fix that I didn't have time for. So I pulled the battery and left it for the morning before work.

4. The next morning I went to the Team Octos homepage using my laptop and that's when it hit me- their homepage shows the download links for their newest Android Marshmallow ROM, NOT Android L like I had expected (L is now hidden under a new submenu on their site). So

I had mistakenly installed M and caused these Google Play issues.

That's my own fault, having missed that one letter that was different in the file name because I was browsing using my phone instead of my laptop, like I have always done before.

5. Thankfully, I have the previous L rom in my SD card. So I booted into TWRP and tried installing that ZIP, wiping cache, dalvik and fixing permissions before booting to system. All I got was an infinite bootloop, never even getting to the home screen.

6. Then I got progressively deeper- I reinstalled the L ROM and the OpenGApps package I had originally installed with the build. With every install and reboot, I cleared the cache, dalvik and fixed permissions as well. Still nothing but a boot loop.

7. Next time in TWRP, I went to Wipe > Advanced Wipe > and wiped cache, dalvik AND system (not "Data"). Fixed permissions, reboot. Same bootloop.

8. Next time, I did the above and repaired the file system. Operation was successful, still the same endless boot loop.

9. Next time in TWRP, Restore > restored package from May 31 2015 (farther back than the ROM). This time the phone DID boot to the lock screen, but as soon as the phone is unlocked, I get the following crashes in succession every time I clicked "OK" to dismiss each:

Unfortunately the process android.process.acore has stopped

Unfortunately Themes provider has stopped

Unfortunately the process android.process.acore has stopped

Unfortunately the process android.process.acore has stopped

After the last "OK", the phone restarts and get to lockscreen, unlocks, has the same four crashes, reboots again. By the way, the home screen isn't the home screen- the background is the "welcome to android! Select your language" screen.

And that's where I am now.

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IMPORTANT NOTES:

1. My phone's charging port hasn't been able to securely hold the MicroUSB cable for over a year now, so I CANNOT connect my phone to anything, whether to my computer or a wall charger. All I do is switch out batteries (I have three) whenever my phone is near death. So hardwiring through ODIN, ADB, etc is impossible. I use AirDroid to transfer files over wifi if needed. At this point I can only manipulate files or data using TWRP. Also, the boot process is limited by how long my battery lasts- about an hour or two depending on how hot the phone gets.

2. I CAN take out my MicroSD card and put it into my laptop using a MicroSD to SD adapter. That's ONE way I can put a newer ROM version onto my phone to use through TWRP that way, if needed.

3. I know from copious reading online that this acore process crash can often be fixed by deleting the Contacts cache, or the cache for other apps. Obviously I cannot do that since I can't get past the unlocking of the phone to access any apps since it would require me to set up Android before getting to any phone data outside of TWRP.

4. I want to avoid a factory reset since there is quite a bit of data that is not cloud-synced on my phone that I don't want to lose.

5. Although this is a great excuse to buy a new phone, I'd prefer to at least get this working so I'm not forced to do that and can still recover the data on my S3 first, making that jump on my own timetable instead of being forced to do it in a rush.

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Yes, I know, it's my own fault for mistakenly loading M instead of L without the proper prep. I've jumped from different Android versions before but I did it intentionally and correctly all those times so I know how it's supposed to be done. No need to remind me of how much of a facepalm I caused myself.

The only idea I have now is to attempt to put a new/updated/different ROM version onto my microSD card by putting it onto my laptop first, transferring files and then putting it back into my phone so TWRP can access those files for installation. But I'd rather wait and hear if this is even a good idea before proceeding- I don't want to dig myself into a deeper hole and I'd rather ask for advice.

ANY help would be greatly appreciated. Thank you!