[Google Pixel 4a 5G Guides, News, & Discussion] thomas.raines:
So, I tried some custom roms out there it has caused some really odd issues on this device. The first one I tried was CalyxOs, then lineage, and Proton. All are good roms, but not what I am looking for. But somewhere along the way things got wonky to say the least. Now, I am not blamming any rom or dev for "breaking" my device. I flashed these roms knowing there is a risk, and the roms listed above work for others. I'm pretty confident, there is something I did along the way that screwed things up. Some of the issues I have ran in to:

Before I flash anything, I learned a long time ago, make a backup and transfer all data on sdcard to your pc.

I generally use TTBU. But recently, when I tried to manually drag/drop my sdcard backup to my device, not all files gets transferred over. Basically all the .apk.gz files. Which happens to be the core of the the backup for the apps.

I started using another backup program, oandbackup, which transfers fine. But my apps/data only gets properly restored about 20% of the time. I say 20% because out of 10 flash back to stock and restores, only 2 will successfully work.

When flashing the rom I have been working on, I use lingeage recovery. But what worked yesterday, fails tomorrow. My method has been, flash lineage recovery, flash rom, boot, test rom, flash back to stock, restore. However, it doesn't always work out that way. Sometimes, it will flash fine, I reboot back to recovery and flash gapps, boot system and the loops begin. Flashing a different kernel fixes the bootloop. Oddly though, the stock kernel booted fine on the last flash (mind you, no changes in kernel or rom code). There is a slew of roadblocks and walls I have slammed in to, but this is just to give you an idea as to what I've been trying to work with.

Now, after flashing a custom rom and then flashing back to stock, I always wipe data. But the most recent issue I have encountered, I flashed back to stock. I was on "b" partition. After the initial flash, it boots to fastbootd. Oddly, I was stuck in stock recovery with the little android guy laying on his back. I hit power then vol up and got in to recovery where I selected fastboot and the fashing process continued. After my phone booted, I rebooted back to bootloader, switched to "a" partition, rebooted bootloader, and ran the stock flash script. This way, in my hopes, I would get a fresh and clean flash all the way around. Again, the whole recovery thing happened again, and I resolved it the same way. But when the rom rebooted, bootloops which eventually kicked me back to bootloader. I switched to slot "b" and the rom booted, went thru setup and restored my data, but most apps failed. Luckily, the 1 game I cared about restored this time.

So, yesterday, I wanted to check out stock recovery a little closer, and see if I could use adb. When I tried adb pull <random file on sdcard>, adb did not connect. So, I tried to reboot. Unfortunately, I got stuck at the google boot splash. To recover the device, I had to flash my boot.img.

This morning, I set out on a mission to try and get things fixed back up. I know slot "a" is not bootable, so I figured I would start there. I went to stock images and instead of downloading, I used the online flash tool. nSince I was on slot "b", it flashed to "b" even though I choose to wipe data and force flash all partitions. I tried booting slot "a" but it failed. So, I manually switched to slot "a" and ran the online flasher again. Now slot "a' and "b" both boot successfully. Then I started restoring my sdcard. It is 4.2gb of data. Honestly, not a lot IMO. But it took an extremely long time to restore it. After restoring my sdcard, I ran oandbackup, but I only restored data for 4 apps, which was successful. Everything seems to be running smoothly, and I was able to flash a custom kernel, root, etc with no issues. I guess, when I flash the final beta of my rom, I will see if I got things fixed up or not.

As I write this, I can't help but wonder, what is the root cause of all these issues? One thing I thought of was my cable. I was using one of the usb cables for my oneplus 6t. I switched to the stock cable to test things. I wiped all my data from the sdcard and then restored it with the stock cable. Things went A LOT quicker 928 minutes with op6t cable/2 minutes on stock cable). Since I have things to do today, I have to put this aside for now. But I wanted to get everyone's thoughts and input on this. Have I done something terribly wrong along the way that has caused these issues? Could the cable I was using be the root of all evil in this case? Is this just that wonky of a device, that it has happened to others and a great deal of patience is needed when trying to work on the pixel 4a 5g?