(Long thread warning - But please read and help)

I am using a OnePlus One since a year now and I bought this phone in used condition and asked the dealer to install a custom rom in the device, as the device was old. I think there was Lineage OS system installed with the Android 9.0 version (not sure if what build of 9.0 was I using). The original OS is Cyanogen. The phone worked perfectly fine for a year. There were minute glitches in the OS like camera app sometimes didn't save clicked photos and the system crashed when camera or some other apps were used. Also, the google play store's region settings were also changed and I could not install all apps on the phone. This was the history.

I was using an android charger and cable to charge and it worked all fine with the phone. Unless, my sister who used Huawei phone, used my charger to charge her phone and I observed that my phone charged really slowly. But I ignored it and thought that I will buy the OnePlus One original charger in a few days.

So yesterday, I was using my phone for taking some photos, my phone's brightness was full and I was using the app called B612. I was out in the sun and these days are really hot here (around 45 degree Celsius, Don't know if it is related to my phone's problem or not). My phone was at 52% then. Suddenly, my phone turned off. I tried turning it on again, but it won't start. it starts and shows the OnePlus screen and turns off again and again turns on itself and does the same thing over and over again in a loop. My phone was hot. I tried to turn it off and keep it off, let it rest. I plug it in the charger, it charges normally. But the OS system won't turn on. My data wasn't backed up so I tried to back it up using TWRP recovery 3.3.0 already installed in it. Turned on the recovery mode using the volume down and power button, attached a USB with the phone to transfer my backup, but as soon as I hit the backup button on the recovery mode, the backup process starts and phone shuts down again and starts doing the same loop. I tried cooling it down, again turned it on the next day, but no help. Fastboot mode turns on fine. But when the next day, I tried turning on the recovery mode, the phone won't even turn that on. I don' even know, what to do. Somehow, the recovery started, I wiped the entire phone. Now there's nothing on the phone, no OS. I am planning to install a new custom ROM, but can't even seem to transfer the ROM files using USB, because on attaching USB, no folder appears on the computer although I have MTP mode activated through the recovery. How am I supposed to install a new ROM, when I can't even turn on the recovery, when the recovery shuts down whenever some major process starts. I don't understand what do I do? Please help. I am also uploading some short videos of the phone.

 

Thank you @tommo47 for replying. The phone was almost new when I bought it. It was probably used just for a month when I bought it. About the battery thing, My phone used to be good at battery power even when I charged it with the unoriginal charger. Though it took a long time to charge, probably 3-4 hours for a full charge. I also tried charging it fully when this problem started. I charged it to almost 90% and the phone did turn on with the OS for a while (prob. 15 minutes) as soon as I turned on wifi and apps, it again turned off and never turned on to the point of OS. I still have not got the original charger of the phone. I was about to buy it, but even before that this started happening. Also, when sometimes, I was able to turn on the TWRP recovery mode (a total o two-three times after this problem started appearing), the CPU temperature showed a higher value than before (46 degree celsius) the last time I saw. Also the battery is UNDETACHABLE.

 

@svim Thank you for replying. I'll definitely buy a new battery and an original charger. @svim and @tommo47 Don't you guys think, before buying the battery, I should first install a rom in the phone? As I mentioned earlier, I wiped the entire phone when I was able to turn on the recovery, now basically there's nothing on the phone. Should I install a Rom using fastboot mode and ADB first and then install the new battery? If you guys know, can I install a new recovery software using fastboot mode? if you guys have any links to OnePlus One toolkit, please share. I found a link but it was broken, so can't download it.

 

@Hadron Thanks, but I also tried using a USB-OTG and a flash drive to backup my data and to transfer rom files into the phone so that I could install a new one. But as soon as I would plug in the flash drive into the phone and start a process (let's say backup), the phone would again turn off and turn on again and again in a loop (check the video random turning off and on). So, using a flash drive, USb-OTG didn't help too. I can't check the battery temperature now as I can't access the recovery mode in the phone.

 

But How would I know if the battery issue is fixed if there is no OS installed in the phone?

 

No I plug out the charger. But I'll try to turn it on using the charger still plugged in and let you know.

 

UPDATE (May 26, 2020):

I tried installing a stock bacon rom on the phone using fastboot mood. I downloaded the stock rom from the OnePlus website and used a Wug bacon toolkit. The toolkit displayed that the phone is on bootloop. The stock rom installed fine with every element loaded. The phone turned on displayed the starting one plus screen and then showed the android icon installing stuff. But after that, the same thing happened. Bootloop again started. Is this still an indication of a failed battery rather than a software problem?

 

Thank you!! I am planning to buy a battery for the phone. I will update the here after I get the battery. Thank you all!

 

Hi everyone, I wanted to update the thread here. I was able to buy a new battery and an original charger for phone and as soon as I replaced it, the phone automatically was reverted back to it's Stock CYANOGEN rom. It's working perfectly again. Thank you for all of your support @tommo47 @svim @Hadron @ocnbrze @MrJavi

The advice was really accurate!!