[Android Q&A, Help & Troubleshooting] Lobstercat:
Okay, a dual question here. One specific and one general but they are both related and one will help the other. Hopefully if anyone provides good answers others will find this post useful. I have a Asus Zenfone Selfie which has begun boot-looping. The phone is rooted and has TWRP installed. Once in a while it boots up as far as the home screen, then sometimes only up to the Asus logo. I have flashed several different ROMs (stock and custom) and again, it boots up to the setup screen then only up to the Asus logo so I was assuming this must mean it's hardware related. However, I can boot into TWRP and stay there for hours with no bootlooping. If it were hardware then it should bootloop for TWRP too so it must be software related, right? One more thing: I usually flash in TWRP but many times it crashes during the flash process. Sometimes it does succeed with no issues though. On my PC I might be running some disk or RAM checking tools to see if there was a bad sector or track on my hard drive or a bad module... Yeah, I'm confused. Why is it bootlooping and what, if anything, can I do to fix it?

This leads to my general question. Over the past 20 years I have had several phones, many of which ended up bootlooping. I know the LG G4 & G5 had a hardware flaw that cased them to bootloop and I know screwy flashes can cause bootlooping. But what about all my phones? Some were new, well, only a year or two old, some were 6 or 7 years old. Some were Android, some were Windows Phone. Some were rooted, some were unrooted, some were stock, some were custom ROMs. Some had updated or recently got new apps installed, others hadn't had anything new in ages. Some were in use when they started bootlooping, some were just sitting there. Some had a full charge on the battery, some were close to empty. What can be done to prevent this? What can be done once it has started, especially with one of these newer phones that they STUPIDLY like to make with sealed in batteries. And the given button combination just reboots the phone - again. Depending on who I talk to (or where I read) they say one thing or the other. It's software related. Okay, how? Why? I know on my PC Windows will sometime crash and reboot just for the hell of it, but that's usually just MS fixing an issue with a PC that runs too smoothly. And when that happens, it can be fixed. As an aside to any software developers reading this, I know you may not want to take the time to rewrite everything to work on Linux but you could take a little bit and make your software work with WINE, just a thought guys.

Anyway, so if it's software related, what can really be done to fix it? I can understand the big companies may like it if your phone bootloops so you'll need to buy a new one, but there are tons of developers out there making great custom ROMs. I know they don't have the resources to really fix all the bugs but I assume they would do a better job than certain big companies right? And why would the software suddenly crash like that? Sometimes literally NOTHING is happening, so why the sudden desire to bootloop? What about hardware? Can't we design software to work around the flaw? I would think manufacturers would want to fix problems to make their products as good as they can be but from what we have seen, I guess not. If you read my list above, many of those phones have nothing in common except the bootlooping. So where is the error coming from? Is there really nothing that we can do?

Any ideas and explanations would be appreciated, as would any help on my more recent bootloop device the Asus Zenfone Selfie Z00UD/z00T. Just to mention, that is a newer phone. It may not be now but it bootlooped probably a little over a year ago. It takes me a while to get around to things sometimes, like writing a letter to post on a forum. I had in mind to take it to this one repair shop (they had to replace the USB charging port maybe 3 months before the bootlooping so I assumed there might be a connection) but when I finally got there they told me it was software related and wouldn't look at it. Also, I don't want to make it sound like all my phones bootloop. I have had many many phones that died due to other issues and many more that are still in use, even old ones. I just want to try to understand and grasp any common factors that cause some phones to bootloop, and to maybe use that knowledge to prevent future phones from bootlooping even if I can't repair the ones that already do.

Thanks for your time in reading this and in advance for your answers. If you googled your way here, I hope there is info here that can help you too.